Fuel Efficiency
MANUAL
CONTENTS
Q400 Fuel Efficiency Manual 2
1. Introduction
3
2. Abbreviations
5
3. Summary
8
4. Flight
of Techniques
Planning
11
4.1 Aircraft
Weight
12
4.2 Center
of Gravity (CG)
14
4.3 Auxiliary
Power Unit (APU)
14
4.4 Taxi
15
4.5 Take-Off
17
4.6 Climb
17
4.7 Cruise
19
4.8 Descent
23
4.9 Optimum
4.10 Fuel
Reserves and Contingency Fuel
4.11 Flight
5. Higher
6. Flight
Cruise Altitude
Planning Example
Resolution of SAR Data Using Cost Index Tables
Management
6.1 Enroute
Winds
6.2 Performance
6.3 Approach
Monitoring
and Landing
6.4 Tankering
7. Maintenance
Maintenance
Maintenance
7.3 Dispatch
8. Conclusion
27
28
30
35
36
37
38
38
39
7.1 Airframe
7.2 Engine
25
under MEL and CDL
40
40
42
45
Q400 Fuel Efficiency Manual
3
INTRODUCTION
2.0 INTRODUCTION
Q400 Fuel Efficiency Manual
B!
ombardier’s Q400 NextGen turboprop aircraft has benefited from an
ongoing program of investment and continuous improvement. Since
2000, when the Q400 entered service, the price of fuel has risen
significantly. Airlines are continually seeking solutions to counter the impact of
rising fuel costs and economic challenges. Bombardier has developed a broad
range of solutions and countermeasures to the rising cost of fuel. The Q400
Fuel Efficiency Manual serves as a guide for airlines to maximize their operational and performance techniques, enabling them to generate significant fuel
savings across all mission profiles and phases of flight.
The Q400 NextGen airliner, which is built at Bombardier’s Toronto, Canada
facility, is the most recent development in the evolution of the Q400 aircraft,
and the advanced successor to Bombardier’s Dash 8/Q-Series family of
aircraft. The Q400 airliner was developed after the introduction of regional
jets and is the only turboprop designed to meet the modern definition of
regional flying. Optimized for short-haul regional operations the 70-to-86seat Q400 NextGen aircraft is a large, fast, quiet and fuel-efficient turboprop. Now available with seating configurations up to 86 seats, the Q400
provides an un-matched combination of productivity, passenger comfort
and operating economics with a reduced environmental footprint.
4
2.0 INTRODUCTION
Q400 Fuel Efficiency Manual
The Q400 aircraft is most often used on routes of 200 to 500 NM. As a
modern turboprop, it also has the speed and range to be deployed on
routes up to 1000 NM. The Q400 aircraft’s maximum cruise speed of 360
knots TAS lets the aircraft fly on demand-driven interchangeable schedules
with jets. But, throttle back to 280 knots TAS and the Q400 aircraft is the
most fuel efficient turboprop on a per-seat basis, while providing advantages
in operating cost, speed, passenger capacity and baggage capacity. The
Q400 turboprop delivers the operational flexibility and operating economics
to meet the needs of regional flying in the modern era.
Setting new environmental standards, the Q400 aircraft uses 30 to 40 per
cent less fuel and produces 30 to 40 per cent fewer emissions on routes
where it has replaced similar-capacity, older jets. Importantly, the Q400
turboprops Auxiliary Power Unit (APU), located in the tail of the aircraft,
vents its exhaust and noise upward, resulting in a better operating environment for ground crews. Overall, the Q400 aircraft is 15 decibels quieter than
ICAO Chapter 4 noise standards; raising the bar for the entire industry. The
Q400 aircraft is also participating in biofuel test programs that could make
a significant contribution in reducing aviation’s carbon footprint.
The Q400 aircraft’s high rate of climb, single-engine service ceiling, higher
take-off weight (thus greater payload), optional drop down oxygen system
and jetway-compatibile front air stair passenger door are important factors
that contribute to its operational flexibility. In addition, the Q400’s industry leading navigation capabilities, such as WAAS/LPV, RNP AR, Heads-up
guidance, Coupled VNAV etc contribute to the efficiency of
operations and flight completion rates in challenging environments.
The commercial aviation industry has gone through significant changes
since the recent global recession. The industry’s unwavering focus on optimization and efficiency is the key reason for its resilience. Economic growth
will drive the demand for more aircraft. Rising oil prices and continued price
volatility will drive airlines to accelerate the retirement of older less efficient
aircraft, thereby increasing the demand for new-technology and fuelefficient aircraft such as the Q400.
The Q400 FEH will help airlines find
the optimum fuel efficiency solutions
for today’s challenges, and it provides
the tools to adapt to tomorrow’s
challenges as well.
5
Q400 Fuel Efficiency Manual
6
ABBREVIATIONS
1.0 ABBREVIATIONS
Q400 Fuel Efficiency Manual A/C
AEO
AFM
AOM
APU
BA
CG
CI
FPM
FT, ft
GPU
HSC
IAS
IATA
IFR
ISC
ISA
KG, kg
LB, lb
LRC
ME
MCL
MCR
MIN, min
MLG
MMEL
MRC
MTOW
NLG
NM, nm
OEI
ROD
RPM
SAR
SE
TAS
TOC
TOD
TOW
USG
Aircraft
All Engines Operating
Airplane Flight Manual
Airplane Operating Manual
Auxiliary Power Unit
BOMBARDIER AEROSPACE
Center of Gravity
Cost Index
Feet Per Minute
Feet
Ground Power Unit
High Speed Cruise
Indicated Air Speed
International Air Transport Association
Instrument Flight Rules
Intermediate Speed Cruise
International Standard Atmosphere
Kilogram
Pound
Long Range Cruise
Maximum Endurance
Maximum Climb Power Rating
Maximum Cruise Power Rating
Minute
Main Landing Gear
Master Minimum Equipment List
Maximum Range Cruise
Maximum Take-Off Weight
Nose Landing Gear
Nautical Mile
One Engine Inoperative
Rate Of Descent
Revolutions Per Minute
Specific Air Range
Single Engine
True Air Speed
Top Of Climb
Top Of Descent
Take-Off Weight
U. S. Gallon
7
Q400 Fuel Efficiency Manual 8
SUMMARY OF
TECHNIQUES
3.0 SUMMARY OF TECHNIQUES
Q400 Fuel Efficiency Manual
A!
lthough fuel price and emissions costs have become very important
operational factors, it is important to remember that a minimum
fuel optimized operation is not necessarily the best for every operator, since there are factors and situations that can diminish or negate the
fuel saving benefits, such as:
•
•
•
•
•
•
•
•
•
•
•
Ineffective use of the APU
Start-up delays and taxi speeds
High time-related costs (maintenance, flight and cabin crew, leasing, etc.)
Missing or unfiled ATC clearances
Missing slot times
Airspace access or overflight costs
Passenger related delay costs (missing connecting flights)
Not taking advantage of en-route winds
Reduced weather avoidance capabilities
Poor scheduling
Crew understanding and compliance
For these reasons many operators use a minimum cost strategy. All aspects
of fuel efficiency, such as fuel price, cost of emissions, fuel weight and
tankering can be included in a Cost Index method, which is a method to
minimize total operational cost as a function of all or a selection of operating
variables.
As the purpose of this manual is to focus on fuel efficiency, it will first show
the minimum fuel techniques for ground operations and for each flight segment (climb, cruise, descent, approach and landing), with the understanding that optimizing each flight segment does not always mean that the trip
is optimized; this is further explained in the flight level selection section. It
is up to the operator or flight planning provider to use this knowledge and
data to optimize the overall flight profile.
Next, a few Cost Index methods are explained, followed by practical flight
management recommendations and maintenance implications on fuel burn.
9
3.0 SUMMARY OF TECHNIQUES
Q400 Fuel Efficiency Manual
10
Summary – Fuel Burn Reduction Techniques12
Technique
Aircraft Weight Management
Block Fuel Saving Potential
Up to 1%
C of G Management
Up to 0.5%
APU Usage
Up to 0.7%
Single Engine Taxi
Up to 3%
Climb Technique
Up to 6%
Cruise Technique
Up to 12%
Descent Technique
Up to 5%
FL270 Operation
Up to 3%
Fuel Reserves and Contingency Fuel
Up to 1%
Higher Resolution SAR data
Up to 2%
Enroute Winds
Up to 15%
Visual Approaches
Tankering
Up to 0.5%
Up to 1%
RNP AR Approaches
Up to 3.0%
Airframe Maintenance
Up to 1%
Engine Maintenance
1
2
Up to 0.5%
Individual techniques are not additive and results will vary according to particular conditions
Based on 500 NM
Q400 Fuel Efficiency Manual 11
FLIGHT
PLANNING
4.0 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
A!
flight plan that is accurate in all its components (ground operations,
climb, acceleration, cruise, descent, approach & landing, reserves
and contingency factors) is critical for fuel efficiency. Optimized
routing must be examined, taking into consideration any en-route fees that
may be charged as a result of specific routings. Any optimization benefit must be balanced against the need for accurate and efficient on-time
performance for passenger movements and connections. The impact of a
non-optimal flight planning or carrying unnecessary fuel is multiple:
• cost of additional fuel
• more emissions (CO2, NO)
• additional fuel weight leading to reduced performance, in turn leading
to further limitations and additional fuel required
• payload reduction – when limited by MTOW
4.1 Aircraft Weight
Aircraft weight is one of the key factors in determining the fuel burn. Starting
with an accurate weight on the ground and continuing to have a correct fuel
consumption and aircraft weight estimate for all flight segments will allow
the aircraft route to be planned and flown effectively.
As much as possible, it is recommended to reduce the aircraft weight, as
any excess weight is always detrimental to fuel efficiency. The chart below
shows the Block Fuel3 increment associated with TOW increase, for a
medium sector distance (450 nm).
3
Block Fuel includes: start , taxi-out, take-off , climb, cruise, descent , approach, landing, taxi-in
12
4.1 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
13
For example, if take-off weight is increased by 1% from 58,000lbs to
58,580lbs and with a HSC setting the block fuel will increase by 0.51%,
which translates into 16lbs of fuel.
When the take-off weight is increased, there will be an increase in block fuel.
The table below offers some examples of the fuel increase with an additional take-off weight increase of 1000 lb.
300 nm
450 nm
600 nm
LRC
16 – 20 lb
25 – 29 lb
32 – 39 lb
HSC
6 – 10 lb
7 – 13 lb
9 – 15 lb
An aircraft weight reduction can be achieved by minimizing each of its components: Operating Weight Empty (OWE), payload and fuel.
The OWE is the Manufacturer’s Empty Weight (MEW) plus operational
items. This would include flight crew and their baggage, passenger service
items, manuals, galley supplies, carts, supplementary equipment, and consumables – food, water, etc. An audit should be conducted to ensure only
essential items are carried. The following items could be minimized or
removed entirely:
•
•
•
•
•
•
•
•
•
•
Old magazines and newspapers
Empty galley containers, extra supplies
Excess duty free material (consider removing this entirely)
Extra water in storage tanks
Pillows and blankets
Excessive flight crew baggage
Extra magazines, seatback advertising
Heavy seats, carpets, spare equipment
Flight manuals and documentation (consider an Electronic Flight Bag
Potable water weight implications under normal and MEL use
The MEW tends to increase during operational life due to repairs, upgrades
and moisture accumulation. These weight increments should be monitored
and kept to a minimum.
• Consider drying out insulation
• Keep the aircraft clean and free of dirt (inside and out)
• Infrequent lavatory servicing
4.1 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
14
The Payload weight (passenger + carry-on baggage + checked baggage)
should be accurately assessed by statistical or other methods.
• Where feasible, use actual weights of passengers and baggage
• Assumed or average weights may be limiting
• Optimize weight and balance calculations
• Avoid zonal calculations due to curtailment requirements
• More zones provide a more precise calculation
The total Fuel quantity on board is discussed in Section 4.11.
4.2 Center of Gravity (CG)
The Q400 AOM cruise data is produced based on the aircraft loaded to
the Forward CG Limit. There is lower drag if the aircraft is loaded aft of the
forward limit. The drag reduction improves the fuel burn by approximately
0.04% per 1% MAC change in CG position.
That is approximately 0.76% fuel burn improvement in cruise for a CG shift
from full forward (17%) to full aft (36%), for an aircraft weight of 28690
kg (63250 lb). The effect is reduced for lighter weights (linearly scaled by
weight). For a 1 hour flight at MRC this translates in 3.6 kg (8 lb) fuel saved in
cruise.
4.3 Auxiliary Power Unit (APU)
The Q400 APU/Bleed combination uses an average 1.5 kg/minute
(3.3 lb/minute) of fuel. The fuel burn is reduced by almost half when the
Bleed Air is selected OFF. There is great potential to save fuel and reduce
maintenance costs by reducing APU useage, and the useage of bleed air
from the APU.
APU and Bleed Air (22 deg C)
103 kg/hr (227 lb/hr) or
1.7 kg/min (3.8 lb/min)
APU Only (22 deg C)
53.5 kg/hr (118 lb/hr) or
0.9 kg/min (2 lb/min)
4.3 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
4
Excessive use of the APU can be caused by the following:
•
•
•
•
•
•
•
Inadequate SOP’s detailing the use of the APU
Ground electrical power unavailable
Ground air conditioning unavailable
APU Bleed used on unattended aircraft
APU Generator used on unattended aircraft
Maintenance action using APU instead of Ground Power
APU used for longer turnaround times (greater than 1 hour)
Consider reduction of APU usage when environmental conditions allow (sufficient ambient light and comfortable cabin temperature) and avoid early
starting or running during extended turnarounds. Further, consider closing
window shades/blinds to minimize thermal heating in the cabin. Ensure all
vents are open in the flight deck and cabin to maximize the heating/cooling
effects when the APU Bleed is operating.
When available, the crew should consider the use of Ground Power Unit
(GPU) and air carts when practical and economical, considering cost, time
delays, and noise.
4.4 Taxi
Engine Start
Starting engines during the pushback phase, instead of at the gate may
minimize the fuel burn. However, this would require the APU to be operating
or would require a battery only start. Starting one engine at the gate while
on ground power and then pushing back may be the best alternative and
most efficient method. Delaying the start of the second engine until just
prior to the completion of the pushback procedure will provide additional
savings.
Consider holding the start and pushback procedure if a departure delay is
anticipated.
4
Sector distance: 274nm, cruise segment 197nm, fuel used in cruise: 1056lb
15
4.4 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
Single Engine Taxi
The Q400 average fuel burn for Two Engine Taxi is approximately 12 lb/minute.
The Single Engine Taxi Operations – Considerations and Procedures are
presented in the Q400 AOM, Section 3.4.3.11. The potential fuel savings (for
1 engine operating, one engine shutdown) are on the order of 40% for the
Start and Taxi fuel.
For example, a standard departure that includes a two engine start
followed by a 15 minute taxi will result in a fuel burn of 92.5 kg (204 lb). A
single engine start, followed by a 15 minute taxi and delayed second engine
start will consume approximately 54.4 kg (120 lb) of fuel.
Taxi-out
When multiple runways are available, choose a runway that will minimize taxi
and ground holding times. However, it may be more beneficial to choose a
runway that is aligned with the initial en route heading, even though it may
take longer to taxi. The fuel burn on the ground is much less than the fuel
required to depart in the opposite direction and make the turn en route
while airborne.
Consider the use of intersection departures where applicable to minimize
taxi time. Where possible, choose the most direct taxiing route from gate
to runway.
Taxi-in
Single engine taxi operations could be employed during the taxi-in phase
as well. A reduction in fuel consumption, pollution, noise and brake wear is
possible. It is important that the flight crew consider taxiway surface conditions, taxi time, ramp and parking congestion before employing this strategy.
When waiting excessively for a stand or gate after landing (after the AFTER
LANDING checklist is complete), the crew may opt to select
START/FEATHER on both Condition Levers. The loss of A/C power has no
subsequent effect on the remaining taxi. The difference between DISC/1020
rpm and START/FEATHER is approximately 90 kg/hour (198.4 lb). Once the
gate becomes available, return the Condition Levers to 1020 RPM and wait
for the propellers to unfeather before continuing to taxi.
4.5 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
4.5 Take-Off
Supplement 13 – “Reduced Power” take-off may result in lower overall
engine operating costs as a result of the lower engine temperatures. The
fuel burn benefits of the lower power settings become offset by the extra
time required for acceleration on the ground and when airborne. The
benefits of Supplement 13 are specific to the circumstances of individual
airline operations.
4.6 Climb
Q400 can continuously climb from SL to its maximum operational ceiling
(25000 ft) for any combination of take-off weight, temperature and propeller
RPM. No step climbs are required.
The following climb techniques are currently provided in the Q400 AOM:
• Climb Type 1 (High Speed): is using the most fuel but it takes more
time and the longest distance to Top of Climb (TOC).
• Climb Type 2 (Intermediate Speed): is a speed approximately halfway
between Type 1 and Type 3 climb speeds, and the times, distances and
fuel are approximately averages of the times, distances and fuel to
TOC of Type 1 and Type 3.
• Climb Type 3 (Low Speed): is using the least fuel, it takes the least time
and the shortest distance to TOC (best climb gradient).
• In addition, a Pitch Attitude climb (higher indicated speed, low pitch) is
also considered, as some operators use this technique due to ATC/
operational considerations.
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4.6 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
The climb speed profiles are shown below, in Indicated Air Speed. The Constant Pitch Attitude climb and Type 1 climbs overlap or exceed (in some
areas) the LRC speed. This suggests that for those conditions these high
climb speeds are not the best for a minimum fuel technique, since the climb
is performed at MCL (Maximum Climb power), a power rating which is
higher than any cruise power.
In order to minimize fuel burn for the climb segment, the most fuel
efficient is Climb Type 3. For example, using Type 3 climb instead of Type 1
from SL to FL 160 will save 217 kg (478.4 lb) – 206 kg (454.1 lb) = 11 kg (24.3
lb) which represents 5% in the climb segment. However, upon reaching the
Top Of Climb, the cruise segment will have to be extended to reach the same
point downstream of the Type 1 Top Of Climb. The overall impact of climb/
cruise fuel burn will have to be assessed when optimizing the flight profile.
In addition, climbing at 900 RPM instead of 850 RPM saves fuel by an average 0.5% for the climb segment. The climb time, distance, and fuel data for
all climb types are presented in the AOM for both 850 and 900 propeller
RPM. With the same example conditions as above, but using 900 propeller
RPM instead of 850 RPM, using Type 3 climb instead of Type 1 will save 213
kg (469.6 lb) – 201 kg (443.1 lb) = 12 kg (26.5 lb) which represents 5.6% in the
climb segment.5
5
ISA, 850 RPM, 28000kg (61730 lb)
18
4.7 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
19
4.7 Cruise
The Q400 AOM presents fuel flow, speed and torque in tabular format for
specific weight, altitude and temperature increments for the following:
•
•
•
•
•
•
Maximum Endurance cruise (ME)
Maximum Range Cruise (MRC)
Long Range Cruise (LRC)
Intermediate Speed Cruise (ISC)
High Speed Cruise (HSC)
Maximum Cruise Rating (MCR)
The tabular data in the AOM is derived from charts similar to the example provided below. This chart highlights the Specific Air Range (nm/lb of
fuel) for 3 different weights, and is valid specifically for ISA temperatures at
FL250. The various cruise speed options (listed above) have been added to
the chart for convenience.
Weights
18000 kg
(39683 lb)
24000 kg
(52911 lb)
29574 kg
(65200 lb)
4.7 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
20
The best cruise SAR (best fuel efficiency) is achieved at MRC speed as highlighted below. Simply put, it will provide the furthest distance traveled for a
given amount of fuel burned.
LRC has been historically defined as the speed above MRC that will result in
1% SAR reduction. The benefit of using LRC is that 1% of SAR is traded for
3% to 5% higher cruise speed. The minor fuel burn increase is offset by the
increase in speed and cruise time reduction.
18000 KG (39683 LB)
Cruise Setting
Speed (KTAS)
SAR (nm/lb)
MRC
252
0.2107
LRC
271
0.2086
In contrast, the least fuel efficient but fastest jet-like operation is at MCR
(minimum time). Flying at HSC will trade a small speed reduction (20 kt) for
a significant SAR improvement (7%). The ISC makes a compromise between
a fuel efficient operation and time efficient operation, and is defined as the
average speed between LRC and HSC.
4.7 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
21
29574 KG (65200 LB)
Cruise Setting
Speed (KTAS)
SAR (nm/lb)
MCR
355
0.1426
HSC
335
0.1527
For a relatively short trip, Toronto
(CYYZ) to Montreal (CYUL), the fuel
savings achieved in cruise when
using MRC instead of MCR is 24.2%6,
for an increase in cruise time of 11.6
minutes (35.3%).
Similarly, on a relatively long route,
Toronto (CYYZ) to Halifax (CYHZ),
the fuel savings achieved when
using MRC instead of MCR is also
24%7. The increase in cruise time is
33.5 minutes (35.3%).
6
7
ISA, FL250, 24000 kg cruise weight, 274 nm total distance (cruise portion 197 nm),
Type 3 climb/descent
ISA, FL250, 24000 kg cruise weight, 697 nm total distance (cruise portion 569 nm),
Type 3 climb/descent
4.7 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
If saving fuel in cruise is most important and overall flight time is not a concern8 , the flight crew can use speeds even lower than MRC, leading to further fuel burn reductions. This is illustrated in the following chart, which is
showing the same data as above, but presented in terms of fuel flow (lb/hr).
For flight planning (cruise segment only, or the climb/cruise/descent profile)
it is important to remember that fuel consumption has to be continuously
interpolated and integrated along the flight path using appropriate software
as the aircraft weight, speed, engine power and ambient conditions are continuously changing. The final results are not always intuitive or comparable
when checking against discrete fuel consumption values or hand calculations. The data and discrete values are provided by Bombardier in the AOM.
Bombardier has developed and is offering additional & refined performance
data in our cost index data package.
8
Factors may include favorable enroute tailwinds, fixed arrival time, unavailable/early arrival slots;
short sectors and short cruise sections; flight schedules; or to provide slower speeds, similar to
competition turboprop aircraft.
22
4.8 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
4.8 Descent
A properly planned and executed descent profile can offer some of the
greatest fuel savings. The ideal profile would include an uninterrupted
descent from cruise altitude without the use of any power. This is often
unachievable in busy airspace. Descents that begin too early or late can
also increase the fuel burn. If given a choice, it would be better to begin the
descent early, rather than late. An early (shallow) descent affords the opportunity to regain the optimal profile and find savings in fuel. A late descent
will require in increased rate of descent from the optimal profile, and this
added energy would eventually have to be dissipated through alternative
means – increasing drag, increasing propeller RPM, or a premature level off.
The following descent types are currently provided in the Q400 AOM:
• Descent Type 1, limited by a/c ROD=2000fpm and/or
cabin ROD=300fpm
• Descent Type 2, limited by a/c ROD=1500fpm and/or
cabin ROD=300fpm
• Descent Type 3, limited by a/c ROD=1000fpm and/or
cabin ROD=300fpm
• Descent Type 4, limited by a/c ROD=2000fpm and/or
cabin ROD=500fpm
• Descent Type 5, limited by a/c ROD=1500fpm and/or
cabin ROD=400fpm
The aircraft ROD and cabin ROD limitations are shown on the
illustration below.
23
4.8 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
The actual descent speeds are shown below in Indicated Air Speed.
The most fuel efficient descent segment is achieved with a Type 5 descent,
followed sequentially to Type 1.
Descent Types 4 and 5 provide an overall higher ROD and significant
fuel savings, compared with Types 1 and 2 respectively (up to 40% when
descending from FL250). However, these savings are reduced by a longer
cruise portion as a result of the shorter descent segment. This is very similar
to the “climb - cruise trade off discussed earlier.
In summary, various descent techniques can save up to 5% on fuel burn on a
500nm sector flight.
24
4.9 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
4.9 Optimum Cruise Altitude
From a fuel efficiency perspective, the most important aspect is the block
fuel optimization, not the individual flight segments optimization. For a fixed
sector length, optimizing the individual flight segments does not translate
into overall flight profile optimization. Similarly, when flying jet-like speeds
and profiles, the most important aspect is the block time.
For a given sector length, temperature and wind condition, the most important factor that impacts the block fuel and block time is the cruise altitude,
as that defines TOC position, the cruise segment length and TOD point.
To determine the optimum cruise altitude for each technique, the block
fuel/block time charts are plotted for all sector lengths, altitudes, temperatures and winds, and the optimum altitudes for each technique (minimum
block time, minimum block fuel) are selected for each combination of sector
length, wind and temperature.
The AOM optimum cruise altitudes for a minimum time technique are based
on HSC. The minimum fuel techniques are based on LRC. The related performance is presented in Q400 AOM Section 5.2.
As mentioned before, the only way to accurately perform these calculations
and to integrate the optimum cruise altitudes is by using specialized route
analysis software.
To illustrate this concept (block fuel versus block time), data for different
techniques related to the same cruise speed regimes as presented in the
Cruise section (4.7) are shown below. The chart, for demonstration purposes
only, shows a sector length of 600 nm and three possible cruise altitudes
(FL180, FL220, and FL250)9.
• “High speed, short time” technique
• ISC or HSC
• CL1 / DC1
• “Fuel saving” technique
• MRC or LRC
• CL2 / DC2
9
Both chart assumptions consist of: ISA, 0 wind, IFR Reserves, 100 nm diversion, High TOW
25
4.9 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
26
•
From the chart above:
For a 600 nm sector at FL180, it is possible to complete the “high speed”
flight as follows:
Time
Fuel
Climb 1, ISC and Descent 1
133.7 minutes
2163 kg (4768 lb)
Climb 1, HSC and Descent 1
124.7 minutes
2358 kg (5198 lb)
However, for the same distance and altitude, the “fuel saving” flight
results are:
Time
Fuel
Climb 2, MRC and Descent 2
157.3 minutes
2017 kg (4447 lb)
Climb 2, LRC and Descent 2
150.0 minutes
2035 kg (4487 lb)
4.9 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
Cruise at FL270:
The Q400 maximum operational cruise altitude was recently increased from
FL250 to FL270. The following chart shows the fuel savings that can be
achieved when flying long sector distances at FL270.
For a typical 500 nm sector, fuel savings will equate to approximately 3%.
4.10 Fuel Reserves and Contingency Fuel
Fuel reserves consist of holding fuel, diversion (alternate) fuel, contingency
fuel and extra fuel. On many occasions reserve fuel estimates are conservative;
in some cases the pilots will take extra fuel due to lack of confidence in the
flight planning data, although most of the time the flight planning providers
apply their own safety factors to cover various operational unknowns. The
overall result is that too much reserve fuel is carried.
Holding fuel should be estimated based on Maximum Endurance speed
(ME) since this speed provides the minimum fuel flow. The holding fuel
estimate should also be based on the expected weight at arrival, as the fuel
burn for holding is less at lower aircraft operating weights. The expected
holding altitude may not necessarily be at the standard 1500 ft ASL. If applicable, calculating the fuel burn at a higher assumed holding altitude will
allow for less fuel to be carried. Holding data (including holding in icing with
minimum speed required in icing) are provided in Q400 AOM Chapter 5.10.
27
4.10 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
28
Diversion fuel10 can be minimized in a similar manner to the sector fuel. This
would include using a minimum fuel technique, and optimum cruise altitude
selection for the distance and ambient conditions. Depending on the jurisdiction, choosing appropriate alternates (enroute alternates) allows a reduction of the contingency factor.
Contingency factors are designed to account for meteorological variations
and unforeseen operational constraints. One method to reduce the contingency factor is to take into account seasonal variations and statistical data
obtained from performance monitoring for specific routes and flight profiles.
Another method is to consider decision / diversion points along the route.
Overall, contingency factors can be reduced from very conservative 5% or
6% to more accurate and realistic 2% to 3%.
Extra (discretionary) fuel should not be added without a good reason, as it
might duplicate reserve fuel components already accounted for in the flight
planning, and unnecessarily increase to overall aircraft weight11.
An accurate fuel reserve estimate should be tailored to route specific operational and weather conditions, and be very close to the minimum required
by regulations.
4.11 Flight Planning Example
The flight planning example below illustrates the impact of using the fuel
saving methods described in this manual. A typical high speed operation12
can be optimized for minimum fuel13 with the following procedures:
Fuel Saving
Action
OWE reduction
Payload estimate
TOW
10
11
12
13
Typical
High Speed Optimized for
Operation Minimum Fuel
Savings
Savings
% of Block
Fuel
kg/(lb)
17819 kg
(39284 lb)
17690 kg
(39000 lb)
-
-
8489 kg
(18715 lb)
8339 kg
(18385 lb)
-
-
29574 kg
(65200 lb)
28476 kg
(62780 lb)
-
-
Using the flight planning standard of 100 nm or actual diversion/alternates
Operators employing a Flight Efficiency program highlight this topic as one of the most difficult to
convince Flight Crew to adhere to, but result in large savings. Flight Crew awareness and compliance is critical.
Sector length – 500nm, ISA, IFR Reserve – 45 min
“Typical High Speed Operation” and “Optinized for Minimum Fuel” calculations are performed with
the same route analysis program and database.
4.11 FLIGHT PLANNING
Q400 Fuel Efficiency Manual
Fuel Saving
Action
APU Bleeds (ON/
OFF)
29
Typical
High Speed Optimized for
Operation Minimum Fuel
Savings
Savings
% of Block
Fuel
kg/(lb)
34 kg
(76 lb)
18 kg
(39 lb)
16.8 kg
(37 lb)
0.7%
93 kg
(204 lb)
54 kg
(120 lb)
38 kg
(84 lb)
1.6%
Take-Off
42 kg
(93 lb)
42 kg
(93 lb)
Air Manoeuvre
28 kg
(62 lb)
-
28 kg
(62 lb)
1.2%
324 kg
(715 lb)
375 kg
(827 lb)
50 kg
( – 112
lb)
-2.2%
Cruise altitude
23000 ft
27000 ft
-
Cruise Speed/
Winds/CG
1335 kg
(2944 lb)
897 kg
(1977 lb)
439 kg
(967 lb)
18.8 %
Descent Type/
ROD
318 kg
(703 lb)
166 kg
(365 lb)
153 kg
(338 lb)
6.6 %
App./Landing/
RNP
89 kg
(196 lb)
22 kg
(49 lb)
67 kg
(147 lb)
2.9%
Taxi-in (SE/AE
Taxi)
93 kg
(204 lb)
54 kg
(120 lb)
38 kg
(84 lb)
1.6%
Reserve altitude
5000 ft
10000 ft
817 kg
(1802 lb)
Diversion fuel
Contingency
factor
Taxi-out (SE/AE
Taxi)
Climb Type/RPM
-
-
-
-
-
532 kg
(1172 lb)
286 kg
(630 lb)
-
413 kg
(912 lb)
362 kg
(799 lb)
47 kg
(103 lb)
-
6.00%
2.00%
Total Reserves
1359 kg
(2997 lb)
924 kg
(2038 lb)
Block Fuel
2329 kg
(5135 lb)
1628 kg 700 kg
(3590 lb) (1545 lb)
30.1%
Trip Fuel
2138 kg
(4713 lb)
1502 kg
636 kg
(3311 lb) (1402lb)
29.7%
Reserve fuel
-
-
-
-
Q400 Fuel Efficiency Manual
30
HIGHER RESOLUTION
OF SAR DATA USING
COST INDEX TABLES
5.0 COST INDEX
Q400 Fuel Efficiency Manual
The Flight Planning section presented fuel efficient methods for ground
operation, and each individual phase of flight. These methods can be used
either separately, or for trip optimization, within a simple (static) or a
dynamic Cost Index solution.
Total Cost = Fixed Costs + Time Dependent Costs + Fuel Cost
Cost Index is a concept or a tool used to minimize the total operational cost,
not necessarily isolated to minimize fuel burn. Cost Index is defined as the
ratio of time-related costs to fuel-related costs, and is specific to each operating environment and each operator, since every operator has different
routes, marketing strategies and cost structures.
Cost Index can be measured in:
Cost ($)/minute : Cost ($)/kg fuel = kg fuel/minute
For example, the ratio of “100 kg fuel : 1 minute” shows that from a cost
perspective 100 kg of fuel can be traded for 1 minute of flight, or vice versa,
while maintaining the same operational cost.
31
5.0 COST INDEX
Q400 Fuel Efficiency Manual
The fuel related cost is really just the price of fuel on board; however the
time dependent cost is influenced by many factors. The most important
time dependent costs are related to:
•
•
•
•
flight crew salary and benefits
maintenance and overhaul intervals
missed connecting flights
late flight charges and expenses
Each of these costs can be further analyzed and quantified. For example,
the cost of an arrival delay (missing connecting flights):
• can rise sharply in discrete steps and raise sharply to high amounts as
more and more people lose connections
• can be quantified and it can help to determine the recovery plan, and
be modeled in a (dynamic) Cost Index, when fuel savings are negated
by arrival delay costs
A modern, efficient and safe flight planning requires consideration of many
operational aspects (weather, navigational data, airspace rules and restrictions) and advanced flight management (optimum vertical and horizontal
flight profile, at optimum speed), as the optimum altitude and speed change
with time, weight and weather. All the operational aspects can be correlated
with costs by using a dynamic Cost Index method.
IATA14 identified that the main impediment for fuel efficient operations is the
lack of sophisticated Flight Planning tools (i.e. Cost Index methods). Using
Cost Index methods has the biggest savings potential once it is
developed, understood and correctly implemented at each level/department in the organization (management/accounting, maintenance, flight
planning, dispatch, flight crew) and continuously monitored and adjusted.
With various Cost Index methods and other fuel saving initiatives, there
is always a risk of confusion with regards to “who” is saving either fuel or
money, at what level and how, which can lead to conflicting strategies and
overall inefficiencies.
Flight crews need to be aware that a properly implemented Cost Index
takes into account not only operational, but more importantly business decisions, and that they do not always have visibility to all the factors considered
when required to fly a specific Cost Index.
14
Guidance Material and Best Practices for Fuel Management, 1st Edition 2004
32
5.0 COST INDEX
Q400 Fuel Efficiency Manual
If a Cost Index solution is developed, or the flight profile is already
optimized either for minimum time, optimum cost or minimum fuel, it is detrimental if the flight crew deviates from the plan. However, the flight crew
need to be aware of the plan, and be able to make good and safe decisions
when operational restrictions or weather changes require deviations.
Ideally, the crew should have the Cost Index tools (FMS, EFB, in-flight support from ground stations, etc.) and the capability to re-optimize when flight
milestones or enroute changes occur.
A sophisticated, dynamic Cost Index solution is a software solution that can
access and use performance, financial, weather and operational data
in real time.
Bombardier has made available a detailed Cost Index performance data
package to support flight planning/cost index solutions.
The Q400 Cost Index Data package consists of detailed high resolution
climb, cruise and descent performance digital data (AEO and OEI) in small
increments of weight, altitude, temperature and speed, in a generic, easy to
use and implement format.
33
5.0 COST INDEX
Q400 Fuel Efficiency Manual
For example, with reference to the SAR chart below, the Cost Index Data
is provided in additional speed increments of 7 kt, additional weight increments of 227 kg (500 lb), temperature increments of 2 degrees C, and
altitude increments of 500 ft. This Cost Index data set has vastly more information as opposed to the AOM, which for practical reasons, shows only the
six cruise regimes described earlier in this document
Therefore, the Q400 Cost Index Data allows for a higher accuracy in all optimization calculations, eliminating linear interpolation and other related errors,
which will result in a more accurate cruise fuel burn estimate by 2% to 10%.
34
Q400 Fuel Efficiency Manual
35
FLIGHT
MANAGEMENT
6.1 FLIGHT MANAGEMENT
Q400 Fuel Efficiency Manual
6.1 Enroute Winds
The effect of predicted enroute winds (tailwinds or headwinds) are considered in the dispatch flight planning and eventually can be reconsidered in
flight, when advantageous. Cruise altitudes can be changed, either to take
advantage of tailwinds or to alleviate the effect of headwinds.
For example, the chart below shows the influence of headwinds on SAR, for
a LRC cruise segment at different altitudes. The chart illustrates how it is
possible to estimate if a cruise altitude change would be beneficial.
In this specific example, in order to maintain the original SAR of 0.1300 nm/lb
fuel planned for FL210, zero wind, an unpredicted headwind of 25 kt would be
alleviated by climbing to FL230 .
Or, reading left to right in the chart, the same SAR of 0.1300 nm/lb can be
achieved if climbing to FL250 with a 50 kt headwind.
The effect of en-route winds is best accounted for within a flight
planning or a Cost Index software program, since the winds are dynamic
and frequently changing.
36
6.2 FLIGHT MANAGEMENT
Q400 Fuel Efficiency Manual
6.2 Performance Monitoring
Aircraft and engine performance monitoring (airspeed, torque, RPM, fuel
flow, fuel quantity on board, correlated with the aircraft weight and the
actual ambient conditions) is highly recommended, as it allows to identify
trends in engine fuel flow, airframe drag and overall trends at aircraft level.
Performance monitoring also allows the statistical assessment of the flight
planning accuracy and the potential reduction or customization of fuel
contingency factors. Performance monitoring is often a regulatory audit
requirement for IATA Operational Safety Audit (IOSA).
It is very useful to have a record of fuel on board at critical points: Take-Off,
TOC, TOD, and fuel remaining at destination. This data will help identify specific areas of flight planning or Cost Index methods that need to be further
addressed or refined. This data should be recorded from the actual fuel indications, and not be taken from the FMS.
37
6.3 FLIGHT MANAGEMENT
Q400 Fuel Efficiency Manual
6.3 Approach and Landing
Whenever possible and safe, shorten the approach procedure. When practical and permitted, the flight crew can choose to fly a visual approach in
order to save both time and fuel. Properly programming the FMS and aligning
the descent with the approach will also help reducing the fuel burn.
The advantages of new technology, including RNP, can offer significant
savings by shortening approaches and reducing track miles, which equate
to fuel savings. Operators have reported saving anywhere between 5 – 40
track miles with the advent of SID’s or STAR’s. The savings can amount to
over 3% of block fuel.15
A decelerated approach (low noise, low drag) can lower fuel consumption
and reduce noise. Keeping the aircraft clean, delaying flap and gear selections will help increase the fuel savings.
Consideration should be given to the flap setting used on landing. Maximum
flap will have increased drag, and may not be optimum on approaches or
runways that do not require their use. Reduced flap landings, where applicable, can offer savings.
6.4 Tankering
For each type of operation, especially for return routes, a specific tanker/
transport coefficient should be derived. Using route analysis or flight planning software, it will be easy to determine the ratio of fuel price at the origin
airport compared to the fuel price at the destination airport, and whether it
is economical to transport (tanker) fuel. This data can be further refined to
determine the optimal tankered fuel quantity.
When tankering, always remember to consider the impact on TOW,
payload and landing weight limitations. The cost of tankering can be determined using the chart presented in 4.1.
15
34 nm savings on approach due to RNP capabilities can equate to roughly 180 lb of descent/
approach fuel. Assuming a block fuel of 2610 lb, this equates to 6.9% total savings.
38
Q400 Fuel Efficiency Manual
39
MAINTENANCE
7.1 MAINTENANCE
Q400 Fuel Efficiency Manual
7.1 Airframe Maintenance
As airframe deterioration is expected over the aircraft operational life16, it
is important to efficiently maintain the aircraft operational efficiency by performing regular airframe inspections and performing repairs or adjustments
when required.
The following represent items with the highest potential to have a negative
impact on aerodynamic performance and therefore on fuel efficiency:
• rough surfaces
• paint condition
• dents, blisters, gaps
• surface mismatches
• door seals, panel seals and wheel well doors
• fairings, engine nacelle
• flight controls rigging
• dirt, oil leaks, other contamination
• airframe asymmetry (following ground or other impacts)
Bombardier has created an Aircraft Economics Working Group to further
reduce the per hour operating cost of the aircraft. To date, the hourly operating cost has been reduced by over $75 with various maintenance related
initiatives.17
7.2 Engine Maintenance
Monitoring engine performance allows for the determination of fuel consumption degradation. This will help in determining the savings expected
from maintenance performance improvements versus the cost to perform
these activities or refurbishments. All these aspects should be reviewed in
detail with the engine manufacturer.
The best plan for maintenance of good engine performance is to maintain
the engine gas path as close to original condition as possible, in terms of
parts surface condition and compressor and turbine running clearances.
This involves cleaning, repairing and replacing components as required, and
accepting certain conditions in accordance with AMM and Engine Manuals
and CIR. Defining the extent of a work scope is a decision between cost and
engine turn time versus expected gains in performance.
16
17
Airframe components include but are not limited to doors, panels, flight control surfaces, fairings,
seals, engine nacelle, etc.
AEWG improvements since 2005 can be found on www.iflybombardier.com
40
7.2 MAINTENANCE
Q400 Fuel Efficiency Manual
The following elements have a negative impact on fuel burn:
•
•
•
•
FOD
dirty compressor
shroud rubbing
HP and LP turbine blade increased tip to shroud clearances.
General recommendations are:
• The LPC1 rotor should be examined for leading edge foreign object
damage and erosion. In situ repairs may be carried out in accordance
with approved manuals
• Perform a performance recovery wash on a routine schedule
• Engine shop visit for HSI or overhaul will re-establish the proper
clearances and parts condition to improve on engine performance
hence lower fuel burn.
Performance recovery wash is a detergent wash which has significant performance recovery potential, hence direct fuel savings. Detergent washing is
recommended to be performed on a routine schedule; the interval is to be
optimized based on visual inspection of the compressor rotors. An engine
wash can recover 0.5% in terms of fuel efficiency.
41
7.3 MAINTENANCE
Q400 Fuel Efficiency Manual
42
7.3 Dispatch under MEL and CDL
The Master Minimum Equipment List (MMEL) allows for higher dispatch
reliability. However, some of the MMEL items have significant impacts and
impose additional restrictions on flight planning (either altitude, temperature,
speed or weather limitations). These limitations bring fuel consumption penalties by not allowing optimum flight planning, for example by not flying at
the optimum altitude, or by having to fly above/below/around icing conditions. In the context of maximizing fuel efficiency, these MMEL items should
be fixed or replaced as soon as possible:
Component
Condition
Limitation
21-30-1 CABIN PRESS
Warning Light
Inoperative
Max altitude: 10000 ft
21-30-2 CABIN ALT Indicator
Inoperative
Max altitude: 10000 ft
21-30-3 CABIN DIFF
Press. Indicator
Inoperative
Max altitude: 10000 ft
21-30-4 CABIN RATE Indicator
Inoperative
Max altitude: 10000 ft
21-30-5 Cabin Pressure
Control System
AUTO &
Max altitude: 10000 ft
MAN modes
Inoperative
21-30-6 Aft Valves Indicator
Inoperative
Max altitude: 10000 ft
27-30-2 Stick Shaker
Inoperative
No flight in icing
27-30-3 Flap Discrepancy
Inoperative
No flight in icing
27-30-4 Stall Warning
Inoperative
No flight in icing
27-30-5 Stick Pusher
Inoperative
No flight in icing
28-40-2 Fuel Tank Temperature
Indication, if using Jet B/
JP-4 fuel
Inoperative
Max altitude: 20000 ft
30-10-1 TAIL De-Ice Boots
Advisory Lights
Inoperative
No flight in icing
30-10-2 DEICE PRESS
Caution Light
Inoperative
No flight in icing
30-10-3 DEICE PRESS
Indicators
Inoperative
No flight in icing
30-10-4 Low Pressure
Warning Switches
Inoperative
No flight in icing
7.3 MAINTENANCE
Q400 Fuel Efficiency Manual
Component
43
Condition
Limitation
30-10-6 Timer Monitor Unit
Inoperative
No flight in icing
30-10-7 Airframe De-Icing
Inoperative
No flight in icing
30-20-2 ENGINE INTAKE HTR
Advisory Lights
One
Inoperative
No flight in icing
30-20-4 Engine Intake Adapter
Heater Assemblies
One
Inoperative
No flight in icing
30-30-1 Pitot/Static Heaters
Two
Inoperative
No flight in icing
30-30-2 Pitot HEAT 1, 2, STBY
Caution Lights
Inoperative
No flight in icing
30-40-2 Windshield Heaters
One
Inoperative
No flight in icing
30-60-1 Propeller De-Icing
Inoperative
No flight in icing
30-80-2 Ice Detector Probes
Inoperative
No flight in icing
32-30-1 Landing Gear
Inoperative
Max speed: 215 KIAS
Retraction System
AFM Supp. 94
Max altitude: 20000 ft
35-20-1 Passenger Oxygen
System (APPOS)
Inoperative
Max altitude: 13000 ft
36-10-1 Bleed Systems
One
Inoperative
Max altitude: 10000 ft
52-10-2 Door Seal Drain
Valve Open
Inoperative
Max altitude: 10000 ft
71-60-1 Engine Intake
Bypass Doors
Doors
Inoperative
No flight in icing
71-60-1 Engine Intake
Bypass Doors
Inoperative
Open
Max Temp. = ISA+25
7.3 MAINTENANCE
Q400 Fuel Efficiency Manual
44
Similarly, the Q400 AFM Supplement 41 Configuration Deviation List (CDL)
allows the airplane to be operated with certain missing parts that cause
a performance degradation or limitation. In the context of optimum flight
planning and fuel efficiency, the following should be replaced as soon as
possible:
Component
Condition
Limitation
30-1 Wing Root Cold Bonded
Leading Edge De-ice Boot
One
Inoperative
No flight in icing
30-2 Engine Intake De-ice Boot
One
Inoperative
No flight in icing
32-1 MLG Shock Strut
Performance limited
Fairings All
Inoperative
weight reduced
by 450 kg
32-1 NLG Aft Doors
One
Inoperative
Maximum Speed =
190 KIAS
Q400 Fuel Efficiency Manual
45
CONCLUSION
8.0 CONCLUSION
Q400 Fuel Efficiency Manual
F!
uel efficiency is very important and there are many ways of improving it, as shown in this manual. However, it is always important to
remember that fuel efficiency is just one component of an overall
cost efficient and safe operation.
Summary of best practices:
• flight plan using accurate data and minimum fuel techniques
• fly at speeds and at altitudes appropriate to economic priorities when
using a cost index method
• use flight planning based on contingency factors derived from aircraft
performance monitoring
• ensure proper maintenance of engine and airframe; avoid significant
MEL/CDL items
The data presented in this manual are for illustration and not subject
to regular revisions. They are not intended to replace or amend any data,
procedures or recommendations presented in the AFM or AOM. For operational use and flight planning, always refer to Q400 AFM, AOM and Cost
Index Data.
Recommended additional reference: IATA Guidance Material and Best Practices for Fuel and Environmental Management – including the Efficiency
Checklist.
For any observations, comments or questions, please contact Technical
Help Desk at thd.qseries@aero.bombardier.com
Bombardier would like to recognize the leadership shown by Flybe with
their Fuel Efficiency program, and would like to thank Ben Davies, Chris
Nagle, and Chris Coney Jones for their individual contributions to this effort.
46