FREEWHEELING UNIT/MAIN DRIVE SHAFT CONNECTION TO THE TRANSMISSION
1. State the purpose of the power train system.
The power train system provides a means of transmitting engine power to the main and tail rotor systems.
2. State the purpose of the freewheeling unit/sprag clutch assembly.
The sprag clutch, in the freewheeling unit, provides a disconnect from the engine enabling autototational
forces to drive the transmission, tail rotor, and all transmission mounted accessories in the event of an
engine failure.
3. What is the lubrication source for the freewheeling unit?
The freewheeling unit is lubricated by transmission oil.
4.
Does the freewheeling unit have a chip detection capability?
Yes, but the chip detector is not electrically wired for a “caution light” indication in the cockpit.
5. What does the main driveshaft connect?
It is a flexible coupling that connects the freewheeling unit to the transmission input drive.
6.
Why is the main drive shaft a flexible coupling?
The movement between the transmission (a floating pylon mount) and the freewheeling unit mounted on the
engine (a rigid mount) requires coupling.
7. In the event of an engine failure, what drives the tail rotor in autorotation?
The main drive shaft transfers transmission RPM (inflow of air through the rotor system) to the
freewheeling unit to drive the tail rotor.
CHARACTERISTICS OF THE MAIN TRANSMISSION
1. What mounting technique is used to secure the transmission to the airframe?
An isolation mounting technique (it is not rigidly mounted)
2. What is the purpose of the pylon support links?
To mount the transmission to the airframe and bear the aircraft’s weight.
3. What effect does a focused pylon mount have on the transmission?
A focused pylon mount lowers the CG of the transmission. This reduces the transmission’s movement.
4.
Why is the transmission mounted with a 5º forward tilt?
To provide a more comfortable attitude in forward flight.
5. Why is the transmission mounted with a 1.25º tilt to the left?
To help compensate for translating tendency.
6. What does a rubber isolation mount provide?
A rubber isolation mount provides for lateral centering and shock absorption.
7. What does the drag link’s round pin and the pylon stop’s square hole provide?
Positive travel limits for the pylon.
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CHARACTERISTICS OF THE LUBRICATION SYSTEM
1. Where does the TRANS OIL TEMP caution light get its information?
From the switch located on the transmission oil filter’s housing.
2. Where does the transmission oil temperature gauge get its information?
From the thermo bulb/transducer on the oil filter’s housing?
3. Does the transmission oil cooler have a bypass capability?
The transmission oil cooler has a thermal bypass at temperatures below 71 ºC. Above 81 ºC the bypass
valve closes and the oil must be cooled.
4. How is the transmission oil cooled?
A flexible duct/hose assembly transport cooling air from the engine oil cooler housing to the transmission
oil cooler where some air about to cool the transmission oil is scavenged to cool the hydraulic reservoir.
5. How many chip detectors are there on the transmission oil system?
There are four transmission chip detectors (sump, pump, chip pan, and freewheeling unit) on the oil system.
6. How many chip detectors are there on the transmission that can activate the TRANS CHIP caution light?
There are three chip detectors (sump, pump, chip pan) that can activate the TRANS CHIP light.
7. Where is the transmission oil level sight glass located?
The sight glass is located on the right side of the transmission.
CHARACTERISTICS OF THE MAST
1. What are the three splined areas on the mast?
The mast is splined to the planetary gear case, the collar set, and the trunnion.
2. Why is the mast hollow?
A hollow mast is stronger, flexible, and lighter weight.
CHARACTERISTICS OF THE TH-67 TAIL ROTOR POWER TRAIN SYSTEM
1. How many tail rotor drive shaft segments are there?
There are eight tail rotor drive shaft segments. Two are made of steel, and six are aluminum alloy.
2. How many tail rotor drive shaft segments are on top of the tail boom section of the aircraft?
Five of the eight tail rotor drive shaft segments are on top of the tail boom.
3. What are the hanger bearing assemblies used for?
Hanger-bearing assemblies are used to support the drive shaft and maintain drive train alignment in its
position over the tail boom .
4. What is used to connect a drive shaft segment to another component?
Thomas couplings are used at every drive shaft connection to provide a strong yet flexible connection
requiring no lubrication.
5. Why are the indexing flats in Thomas couplings alternated?
Alternating indexing flats increases the tensile strength in these flexible couplings.
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6. What is used to prevent slipping when the last tail rotor drive shaft segment is attached to the tail rotor
gearbox?
A splined adapter is used to prevent slipping.
7. Why are breather type filler caps used on the tail rotor gearbox?
Breather type filler caps are used to prevent “pooling and cavitation”.
8. What caution light illuminates when ferrous metal particles complete the circuit on the tail rotor gearbox
chip detector?
The T/R CHIP caution light illuminates when ferrous metal particles complete the circuit on the tail rotor
gearbox chip detector.
CHARACTERISTICS OF THE MAIN BATTERY SYSTEM
1. What is the rating of the SLAB battery?
The SLAB battery voltage is 24 VDC 17 amps.
2. Where is the battery switch (BATT/OFF) located?
The battery switch is located on the overhead console.
3. What recharges the battery?
The generator recharges the battery in flight.
4. Can the batteries level of charge be checked during flight?
Yes, the generator must be on as the battery switch is turned off. The drop observed on the load meter
indicates how much of the generator’s load was devoted to recharging the battery.
5. What indicates a fully charged battery?
A drop of less than 1% indicates a fully charged battery.
6. What measuring gauge is used to measure 1%?
The thickness of a secondary line is the measuring gauge for 1%.
THE VFR AND A+ ELECTRICAL SYSTEM
1. What does the starter component of the starter/generator do during the starting sequence?
The starter component turns the N1gear train to drive the accessories necessary for basic engine operation.
2. What does the generator component of the starter generator do after the engine is running?
The generator provides 28 VDC to the aircraft’s electrical circuits, plus it maintains charge of the main
battery that is in the nose of the helicopter.
3. How many buss bars are there in the VFR and A+ configuration?
There is one main buss bar in the VFR and A+ configuration.
4. What is the purpose of a buss bar?
A buss bar distributes electrical power.
5. What is the starter/generator rated at?
The starter/generator is rated at 28 VDC and 105 amperes.
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6. What are the power sources for starting the VFR and A+ configured aircraft?
The battery in the nose of the aircraft and the auxiliary power unit.
7. During normal operations, what are the power sources for the VFR and A+ configuration?
The generator is the primary source with the battery as a backup power source.
8. How long will the battery power the electrical systems after the generator has failed?
There are too many variables to predict battery life in terms of time after generator failure.
THE IFR ELECTRICAL SYSTEM
1. How many direct current power sources are available for normal operations in the IFR configuration?
There are three DC power sources (main generator, stand-by generator, and main battery) available for
normal operations in the IFR configuration.
2. What is the rating of the main generator?
The main generator is rated at 28 VDC direct current and 105 amperes.
3. What is the rating of the stand-by generator?
The stand-by generator is rated at 28 VDC and 15 amperes.
4. What is the rating of the main battery in the nose of the helicopter?
The main battery is rated at 24 VDC and 17 amperes.
5. What does the voltage monitoring system allow the pilot to monitor?
The voltage monitoring system allows the pilot to monitor generators, batteries, and buss bars voltage.
6. What does an inverter do?
An inverter converts direct current voltage to 115 volts alternating current (AC) to run two elements to the
avionics package.
7. What is the rating of the stand-by battery?
The stand-by battery is rated at 24 VDC.
8. How many buss bars are there in the IFR configuration?
There are three buss bars (ESS 1, ESS 2, and non-ESS) in the IFR configuration.
9. Which buss bar is the most protected?
The pilot’s buss bar (ESS 1) is the most protected buss bar.
10. Following the main generator’s failure (MAIN GEN FAIL) what powers the ESS 2 buss bar?
The main battery powers the ESS 2 buss bar in the event of the main generator’s failure.
11. Following the main generator failure (MAIN GEN FAIL) what powers the non ESS buss bar?
The main battery powers the NON ESS buss bar provided the NON ESS switch is placed in the MANUAL
position; otherwise the NON ESS circuits are shed from the battery’s load.
12. In the IFR configuration, how many power sources are there for starting?
There are two power sources (main battery and auxiliary power unit) for starting.
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13. In the event of a dual generator failure (MAIN GEN FAIL and STBY GEN FAIL) and main battery power
becomes depleted, what powers the stand-by attitude indicator?
The stand-by battery powers the stand-by attitude indicator for at least 30 minutes.
14. What airspeed should be avoided when the stand-by generator is powering the ESS 1 buss bar?
Airspeed below 50 KIAS should be avoided for prolonged operation when the stand-by generator is
provided power to the ESS 1 buss bar.
CHARACTERISTICS AND COMPONENTS OF THE FUEL CELL
1. How many layers are there in the TH-67fuel cell?
The TH-67 fuel cell is a single layer, crashworthy, bladder based on civilian aviation standards.
2. What is the fuel cell capability and how much of that capacity is consumable?
The fuel cell capacity is 84.1 U.S. gallons of which 82.6 gallons are consumable.
3. What is the burn rate of the Allison C20J turbine engine?
The burn rate is 20-29 gallons per hour.
IDENTIFY THE INTERNAL COMPONENTS OF THE FUEL CELL
1. How many boost pumps are there in the TH-67?
There are two electric fuel boost pumps located in the bottom of the fuel cell.
2. How many fuel quantity-sending units are there in the fuel cell?
There are two fuel quantity-sending units that transmit fuel quantity to an 80 gallon fuel gauge.
3. What caution light illuminates with approximately 12 gallons of fuel remaining?
FUEL LOW is the caution light that illuminates with approximately12 gallons remaining.
4. What is the purpose of the fuel sump drain valve?
The drain valve provides for the taking of a fuel sample or defueling the fuel cell.
IDENTIFY THE EXTERNAL COMPONENTS OF THE FUEL CELL
1. Where is the fuel pressure transducer located and what does it do?
It is located on the right side of the aircraft above the fuel filler cap. It converts a pressure head signal of the
two-boost pumps pressure and sends the higher reading to the fuel pressure gauge.
2. Where is the fuel shut-off valve located and what does it do?
It is located at the extreme top-right portion of the fuel cell above the fuel filler cap. It stops the flow of fuel
when the FUEL VALVE ON/OFF switch is turned off.
3. Where is the airframe fuel filter located and what does it advise the pilot to do?
It is located on the right side of the engine compartment on the forward firewall. It advises the pilot of an
“impending” airframe fuel filter bypass and that the fuel will continue to be delivered to the engine driven
fuel pump.
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IDENTIFY THE FUEL SAMPLING CAPABILITIES OF THE FUEL CELL
1. How is the fuel sump drain valve operated?
It is electrically operated.
2. Where is the fuel sump drain valve located?
It is located forward of the aft cross tube and centered laterally.
3. The fuel valve switch must be in which position for the fuel drain valve to operate?
The fuel switch must be in the OFF position for the fuel drain switch to operate.
4. When taking a fuel sample from the fuel cell, the fuel boost pump circuit breakers should be in which
position?
The fuel boost pump circuit breakers should be in the OUT to prevent sediment and water from circulating
through the fuel system.
5. Where will sediment and water be found in fuel sample jar?
Should there be any water or contaminates in the fuel sample they will be located in the bottom of the fuel
sample jar.
IDENTIFY CHARACTERISTICS OF THE FUEL SYSTEM OPERATION
1. Where is the fuel flow transducer located on the aircraft?
The fuel flow transducer is located on the right side of the engine compartment near the aft firewall.
2. When is the fuel low warning indicating system activated?
The fuel low warning system is activated when 45 minutes of fuel remains at the present consumption rate.
3. The A/F FUEL FILTER caution light illuminates at ______ PSID and bypasses the filter at ______ PSID.
1,4.5
4. How many times is the fuel filtered before it is ignited?
Fuel is filtered four times (A/F fuel filter, engine driven fuel pump, gas producer fuel control, and fuel
nozzle) before it is ignited.
5. A dual boost failure is indicated by ______?
A FUEL PUMP caution light and a fuel pressure drop to zero.
6. A single boost pump failure is indicated by ______?
A FUEL PUMP caution light and a little or no change in fuel pressure.
IDENTIFY THE INFORMATION CONTAINED IN AR 95-1 PERTAINING TO THE CONTROL OF
WEIGHT AND BALANCE OPERATIONS OD ARMY AIRCRAFT
1. What are the pilot-in-command responsibilities?
The pilot-in-command responsibilities are to have a DD Form 365-4 Form F on board the aircraft when
flying; use actual loading when possible; ensure computations are accurate and correct; and to ensure the
center-of-gravity remains between the allowable limits for the entire flight.
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2. What is the definition of class 2 aircraft?
Class 2 aircraft are those aircraft whose weight and center-of-gravity limits can readily be exceed; therefore,
a high degree of loading control is needed.
3. What is DD form 365-3 chart C used for?
DD form 365-3 chart C is used to record any permanent changes in basic weight or center-of-gravity when
the aircraft if modified.
4. Can electronic data sheets be used in lieu of any of the DD form 365 series forms?
Electronic data sheets may be used in place of the DD form 365 series forms provided the information is
identical to that required on the DD form 365 series forms.
5. Can the aircraft be flown if the aircraft’s basic weight has been modified?
The aircraft cannot be flown unless the change in basic weight is accounted for by the proper method.
6. How are permanent changes in basic weight accounted for?
The weight and balance technician accounts for permanent changes by making an entry on DD form 365-3
chart C and creating new forms to replace the old forms.
7. How are temporary changes in basic weight accounted for?
The pilot-in-command accounts for temporary changes in basic weight by using the data recorded on DA
form 2408-13-1 or 2408-14-1 to account for the temporary changes on the forms in the back of the logbook
and flight planning area.
8. Define temporary?
Temporary is defined as 90 days or less.
9. What should be done if the aircraft is not returned to its original condition within the 90-day period?
The DD form 365-3 chart C should be updated to reflect the temporary change and add new DD forms 3654 form F should be created for every typical mission with two sets of copies to replace the expired copies in
the logbook and the flight planning area.
10. How often must all DD forms 365-4 form F be reviewed?
DD form 365-4 must be reviewed every 90 days (365 days, Ft. Rucker policy)
11. How often must all other forms in the file folder be reviewed for currency?
All forms, other than DD form 365-4 form F, must be reviewed every 12 months.
12. Can a new date and initials in the date block extend the currency of DD form 365-4?
If no changes are required the DD form 365-4 form F will be re-dated and initialed in the date block to
certify their currency.
13. When extending the currency of DD form 365-4 and changes are required one must ____________?
Complete a new DD form 365-4.
14. How often should class 2 aircraft be weighed?
Class 2 aircraft should be weighed when the period from the last weighing exceeds 24 months.
15. How often should class 1 aircraft be weighed?
Class 1 aircraft should be weighed when the period from the last weighing exceeds 36 months.
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IDENTIFY THE INFORMATION CONTAINED IN TM 55-1500-342-23 PERTAINING TO THE
WEIGHT TERMS
1. What is the definition for basic weight?
Basic weight is that weight that includes all filled hydraulic and oil systems, trapped and unusable fuel, and
all fixed equipment (this includes the first aid kit and fire extinguisher).
2. What is the definition of operating weight?
Operating weight is that weight that includes basic weight plus crew weight, crew baggage, steward’s
equipment, emergency equipment, and other equipment that may be required.
3. What is the definition of total aircraft weight?
Total aircraft weight is operating weight plus the weight of take-off fuel and water injection fluid if
applicable.
4. What is the definition of zero fuel weight?
Zero fuel weight is operating weight (ref. 9) plus distribution of allowable load, payload, (ref. 13).
5. What is the definition of take-off gross weight?
Take-off gross weight is operating weight plus fuel, cargo, passengers, ammunition, bombs, auxiliary fuel
tanks, etc.
6. What is the landing gross weight?
Landing gross weight is take-off gross weight minus items expended in flight.
7. Can increasing the gross weight of an aircraft affect its performance?
Yes, the take-off/landing distance is increased; hover performance and maneuverability is reduced; rate of
climb, cruising and stalling speed is reduced; hover ceiling, range, and stability is reduced.
IDENTIFY THE INFORMATION CONTAINED IN TM 55-1500-342-23 PERTAINING TO BALANCE
DEFINITIONS
1. What is the definition of moment?
Moment is defined as the tendency to cause motion about a point or axis.
2. What is the formula for moment?
The formula for moment is weight times the arm equals the moment (WxA=M) divided by the index.
3. What is the definition of arm?
Arm is the distance from the reference datum plane to the center of gravity of an item placed in the aircraft.
4. What is the definition of reference datum?
Reference datum is an imaginary plane perpendicular to the longitudinal axis at the nose of the aircraft from
which all measurements of arm are taken.
5. What is the formula for center of gravity?
The formula for center of gravity is total moment divided by total weight equals center of gravity
(TM/TW=CG) multiplied by the index.
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IDENTIFY THE INFORMATION CONTAINED IN THE TH-67 OPERATOR’S SUPPLEMENT
PERTAINING TO WEIGHT AND BALANCE OPERATIONS
1. Which chapter in the TH-67 operator’s supplement is devoted to weight and balance data?
Chapter six in the TH-67 operator’s supplement is devoted to weight and balance data.
2. What is the maximum allowable gross weight for hovering and flight?
The maximum allowable gross weight for hovering and flight is 3,350 pounds.
3. What is the minimum front seat weight for the TH-67?
The minimum single pilot weight is 170 pounds.
4. What class is the TH-67 aircraft?
The TH-67 is a class two aircraft.
5. What does the pilot use the fuselage station chart for?
The pilot uses the fuselage station chart to verify the data that the maintenance personnel place on the DA
form 2408-13-1 or 2408-14-1is correct.
6. Why are there three inches of left cyclic travel and four inches of right cyclic travel depicted on the lateral
vs. longitudinal center of gravity?
There are three inches of left and four inches of right cyclic travel due to the transmission’s tilt of 1.25
degrees left to help compensate for translating tendency.
7. What are the center of gravity charts used for?
The center of gravity charts are used to determine the longitudinal limits at three critical gross weights
(take-off, landing, and zero fuel) to verify full longitudinal cyclic control is available.
8. What are the fuel loading tables used for?
The fuel loading tables are used for determining the weight, arm, and moment of various quantities of
primary and alternate fuel.
9. What should be done if the exact quantity of fuel is not listed on the fuel table chart?
It should be necessary to interpolate if the exact value is not listed on the chart.
10. What table is used for determining the moment of various items placed on board the aircraft by the pilot-incommand?
The cabin and baggage compartment table of moments is used to determine the moments of various items
the pilot-in-command places on board the aircraft at three critical fuselage stations (front seat, back seat, and
baggage compartment).
APPLY THE WEIGHT AND BALANCE INSTRUCTIONS CORRECTLY IN PREPARING A DD
FORM 365-4 DURING A PRACTICAL EXERCISE
1. What side of the DD form 365-4 form F should be completed for the TH-67?
The transport side of DD form 365-4 form F should be completed for the TH-67.
2. Where can the basic weight and moment data be obtained for completing a DD form 365-4?
Basic weight and moment data can be obtained from the last entry on DD form 365-3 chart C in the folder
or from reference 1 on the current DD form 365-4 form F in the logbook or flight planning area.
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3. Should the fire extinguisher and first aid kit’s weight and moment be placed in the emergency equipment
line reference 6?
The TH-67’s emergency equipment is already included in the basic weight entry.
4. Can the aircraft be flown at operating weight (reference 9)?
No, the aircraft is missing useable fuel at the term operating weight.
5. Is the term zero fuel weight (reference14) required to be computed for the TH-67?
Zero fuel weight is required to be computed for the TH-67.
6. If temporary or permanent changes are made in the aircraft’s basic weight, can the aircraft be flown?
The aircraft cannot be flown unless temporary or permanent changes are accounted for.
7. What is the limitations section of DD form 365-4 form F used for?
It is used to provide the pilot with data to make an informed decision in the event of mission changes and
also to verify that the aircraft is within weight and CG limitations.
8. What is the pilot’s rule of thumb for gross weight changes?
For every 30 pounds change in gross weight expect a change in 1% torque.
9. Other than gross weight, what are the other considerations for mission changes at the landing phase of the
mission?
Space and fuel are additional considerations in addition to gross weight for mission changes during the
landing phase of the mission.
10. Which three critical gross weights are used to determine the forward and aft CG limits?
The three critical gross weights that are used to determine the forward and aft CG limits are take-off,
landing, and zero fuel gross weights.
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