KING AIR SERIES COMPONENT MAINTENANCE MANUAL
000
32-10-00
90 SERIES MAIN LANDING GEAR - MAINTENANCE PRACTICES
WARNING: When performing maintenance on a hydraulically operated landing gear system, be aware that
any movement of a hydraulic actuator cylinder can displace hydraulic fluid and cause
unanticipated movement of other actuator cylinders in the landing gear retraction system.
Servicing of the landing gear hydraulic accumulator can also result in unanticipated movement
of an actuator. Either action can result in an unsafe, unlocked landing gear system. Therefore,
place the airplane on jacks prior to performing any inspection or maintenance. Cycle the
landing gear and ensure that all three landing gears are down and locked prior to removing the
airplane from jacks.
Place the airplane on jacks prior to performing any inspection or maintenance. After
performing maintenance of any type on the landing gear system and before releasing the
airplane to service, the landing gear must be cycled from the fully extended to fully retracted
and back to fully extended at least once, checking for proper operation and rigging.
Never service the accumulator or the hydraulic system or do maintenance or rigging of the
landing gear without first placing the airplane on jacks. Stay clear of the wheel wells, landing
gears and gear doors while the landing gear is in operation.
When jacking the airplane in an unsheltered area where winds in excess of 35 knots may be
encountered, never jack more than one gear clear of the ground at a time.
Any time the landing gear is only partially retracted during maintenance, always cycle the gear
with the power pack through at least one complete cycle before removing the airplane from
jacks.
When working on a landing gear or its associated hydraulic retraction system, be aware that
movement of a hydraulic actuator cylinder may cause unanticipated movement of other
actuator cylinders in the system.
MAIN LANDING GEAR - DISASSEMBLY
a. Place the strut in a vertical position to keep the hydraulic fluid from spilling when the filler plug is removed.
Remove the pressure from the strut by removing the cap (3), and depressing the valve core (4) (Ref. Figure 1).
CAUTION: Do not attempt to remove the filler plug body (1) or the valve core (4) before all air pressure is released
from the strut.
NOTE: Do not remove the valve core except for replacement purposes.
b. Cut the safety wire and remove the filler plug body (1) and gasket (2) from the strut. If necessary, the filler plug
can be further disassembled by removing the valve core (4) from the filler plug body.
c.
Remove the snap ring (5) from the top of the strut.
d. Screw a 1/2 inch national fine thread bolt into the filler plug opening for an aid in removal of the support assembly
(6). Slowly lift the support from the strut, allowing the fluid to drain back into the strut. The support may be
disassembled further by removing the ring (7) and gasket (8).
e. Drain the hydraulic fluid from the strut by slowly inverting the strut.
f.
Place the strut in a horizontal position, then remove the attaching hardware and drive the torque knee pins (9)
from the upper and lower torque knees (10 and 11) and remove the torque knees.
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g. Separate the knees by removing the attaching hardware and bushing (12). The lubrication fittings (13) and
bushings (14, 15 and 16) should be removed only if they fail to function properly or are excessively worn. Refer
to Chart 1 for manufacturing tolerances and wear limits.
h. Slide the lower shock absorber assembly (17) from the upper shock absorber assembly (18).
WARNING: The scraper ring (20) may become sharp during normal operation of the gear; care should be
taken when removing the ring to prevent possible injury.
i.
Remove the snap ring (19), scraper ring (20) and the wiper ring (21) from the upper shock absorber assembly
(18).
j.
Pull the felt lubricating pad (22) from the upper shock absorber assembly. Using a suitable length of music wire
(Ref. Figure 1, Chapter 32-20-00), remove the packing (23) from the brazed bearing inside the upper shock
absorber cylinder.
k.
Detach the side brace assembly (24) from the upper shock absorber.
l.
Remove the attaching hardware and pull the top brace casting (25) and the brake tube support bracket (26) from
the strut.
m. If the lubrication fittings (27 and 28), set screw (29) or bushings (30 and 31) do not function properly or are
excessively worn, they should be removed and replaced.
n. Remove the door cam (32) and clamp (33) from the strut.
o. Remove spacer (37) from axle (38). Note the spacer should slide off the axle with little effort. If the spacer has
a tight fit or is stuck, proceed to Step 1. below.
CAUTION: When cutting grooves into the spacer and removing the spacer from the axle, use extreme care not
to damage the axle.
1. Using standard shop practices, cut a groove in the longitudinal axes of the spacer, then cut a second groove
180 degrees from the first cut (Ref. Figure 2). The depth of each cut (groove) should be approximately 70%
the thickness of the spacer.
2. Using a chisel or impact tool, strike the spacer on the edge where each groove (cut) is located (Ref. Figure
2). Repeat until the spacer separates from the axle.
3. Inspect the axle assembly for scoring and nicks (Ref. Figure 1). If damage is found to the axle assembly,
contact the Repair Design Office (RDO) at Textron Aviation Inc. for instructions for return to service.
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
LJ32B
030924AA.AI
Main Landing Gear Assembly
Figure 1
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
Chart 1
Main Landing Gear Manufacturing and Wear Tolerances
NOTE
All dimensions are given in inches (Ref. Figure 1).
The wear limits may vary additionally as long as total joint looseness does not exceed 0.015 inch.
Item
I.D.
O.D.
Remarks
Upper Shock Absorber
Assembly (18)
Internal and Lower End Brazed
Bearings
2.752 to 2.751
2.755 maximum wear tolerance.
Support Assembly (6)
2.428 to 2.425
0.005 maximum wear each side.
Torque Knee Pin (9)
0.624 to 0.623
0.622 maximum wear tolerance.
Bushing (14)
0.6265 to 0.6245
0.628 maximum wear tolerance (reamed at
assembly).
Bushing (16)
0.5005 to 0.4995
0.505 maximum wear tolerance.
Bushing (12)
0.4975 to 0.4955 0.491 maximum wear tolerance.
Bushings (15)
0.3755 to 0.3745
0.380 maximum wear tolerance.
Lower Shock Absorber
Assembly (17)
Tube
2.465 to 2.461
Bolt (36)
2.749 to 2.747
I.D. = 2.475 maximum wear tolerance.
O.D. = 2.746 maximum wear tolerance.
Replace tube if scored or has chipped
chrome.
0.7488 to 0.7481 0.7476 maximum wear tolerance.
Bushing (35)
0.7505 to 0.7495 0.8715 to 0.8700 I.D. = 0.7510 maximum wear tolerance.
O.D. = 0.8690 maximum wear tolerance.
Bushing (31)
0.8755 to 0.8745
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0.8760 maximum wear tolerance.
KING AIR SERIES COMPONENT MAINTENANCE MANUAL
Main Landing Gear Spacer (37) Removal
Figure 2
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
MAIN LANDING GEAR CLEANING AND PARTS REPLACEMENT
Clean all parts with solvent (6, Chart 1, 91-00-00). Check castings for cracks and pitting and finished surfaces for
scoring, pitting, nicks, cracks, distortion and wear. Chart 1 lists manufacturing tolerances and wear limits to aid In
determining the extent of wear. Replace all damaged or excessively worn parts. Replace all packings and DU
Bushings.
MAIN LANDING GEAR - ASSEMBLY
WARNING: To avoid damage to the airplane during maintenance place jacks under all three jack points (one
adjacent to the nose gear and one on each side of the fuselage on the aft spar, inboard of the
nacelle).
NOTE: Any time landing gear components are removed, all parts must be inspected for corrosion before
installation.
a. Check the fit and installation of spacer (37) on axle (38). Nominal clearance should be 0.002 inch ± 0.002 inch
fit between the axle and spacer. Adjust spacer as required to obtain clearance.
b. Install spacer (37) on axle (38) (Ref. Figure 1).
c.
Install the top brace casting (25) on the upper shock absorber assembly (18) and secure it with attaching
hardware. Install the bolt located on the forward side of the strut with the head down.
NOTE: Coat the mating surfaces of the upper shock absorber assembly (18) and the top brace casting (25) with
corrosion preventative compound (21, Chart 1, 91-00-00) prior to assembly. Applications of corrosion
preventative compound at yearly intervals will provide continued protection against corrosion. A light grease
or heavy oil may be substituted for the compound should the latter not be available.
d. With the strut in a vertical position, attach the side brace assembly (24).
e. Insert the packing (23) into the brazed bearing In the shock absorber cylinder from the bottom, using two dowel
rods to work it into the position shown in Figure 1, Chapter 32-20-00.
NOTE: It is recommended to not use hydraulic fluid to lubricate the felt pad (22).
f.
Trim the felt lubricating pad (22) to secure proper fit, soak the material in SAE 10 motor oil or equivalent and
squeeze out the excess oil.
g. Install the lubricated felt pad (22).
NOTE: File the ends of the ring (7) as necessary to obtain a 0.005 to 0.015 inch end gap with the support (6)
installed in the lower shock absorber assembly (17).
h. Install the gasket (8) and ring (7) on the support assembly (6).
i.
Assemble the snap ring (19), scraper ring (20) and wiper ring (21) on the lower shock absorber assembly. The
grooved edge of the wiper ring and the cone of the scraper ring should face the axle.
j.
Install the upper and lower torque knees (10 and 11) and the torque knee pins (9).
k.
Install bushing (12) and join the upper and lower torque knees.
l.
Install the support assembly (6) into the upper and lower shock absorber and secure with snap ring (5).
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m. With the strut fully compressed, fill the strut with hydraulic fluid (9, Chart 1, 91-00-00) to the bottom of the gauge
tube. Work the strut slightly to purge it of trapped air, then refill to the proper level.
n. Install a new valve core (4) in the filler plug body (1) and install the gasket (2) and the filler plug.
o. Secure the door cam (32) and clamp (33). The top edge of the clamp should be 3-11/16 inches from the upper
shoulder of the strut.
p. Inflate the strut to 80 psi air pressure.
q. Apply a soap and water solution in the area of the cylinder cap and upper strut around the brazed joint. Check
the area for leaks. Release air pressure before installing landing gear on the airplane.
r.
Clean the area and install the cap (3) and safety wire.
MAIN LANDING GEAR ACTUATOR - DISASSEMBLY
If the end play between the screw housing assembly (10) and the nut assembly (11) is less than 0.010 inch, the
actuator may be continued in service subject to normal maintenance procedures (Ref. Figure 3).
a. Remove the bolt attaching the clevis (1) to the nut assembly (11) and remove the clevis and spring (2).
b. Remove the shield retaining ring (3), washer (4), packing (5) and shield (6).
c.
Remove packing (7) from the shield.
d. Remove the four bolts attaching covers (8 and 9) to housing (20). Remove the lower cover (9) and any shims
between it and the housing.
e. Remove the screw housing assembly (10), nut assembly (11), top cover (8) and upper bearing (12) from the
housing (20).
NOTE: Prior to removing the screw assembly from the nut assembly, make sure the original position of the nut
assembly is marked on the clevis as specified under MAIN GEAR ACTUATOR REMOVAL in the King Air
90 Series Maintenance Manual. This will ensure proper thread engagement of the double threads of the nut
assembly upon reassembly of the actuator.
f.
Remove the screw assembly from the nut assembly (11).
g. Press cover (8) and bearing (12) off the screw housing assembly.
h. Press grease seal (13) out of the top cover (8).
i.
Remove lower bearing (14).
j.
Remove plug (15).
k.
Remove snap ring (16), then remove pinion gear (17) from the housing by driving on the shaft end. Remove
bearings (18 and 19).
MAIN LANDING GEAR ACTUATOR CLEANING AND PARTS REPLACEMENT
Wash all parts with solvent (6, Chart 1, 91-00-00) and inspect for damage and wear. Replace bearing (14) at
overhaul.
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
NOTE: When replacing bearings (12, 14, 18 and 19), use only the proper replacement bearings as specified in the
applicable Illustrated Parts Catalog.
MAIN LANDING GEAR ACTUATOR - ASSEMBLY
a. Fill nut assembly (11) half full with lubricating grease (4, Chart 1, 91-00-00) (Ref. Figure 3).
b. Screw the nut assembly all the way In by hand to ascertain removal of the excess lubricant and full travel of the
nut assembly.
c.
Manually screw the nut assembly to match the original position as marked on the clevis. If the clevis mark is on
the opposite side, the nut assembly has been installed on the wrong lead thread. The nut assembly must be
removed and rotated 180 degrees for correct installation. The clevis marking will then be on the correct side.
d. Slide upper bearing (12) over screw assembly (10) and insert the entire assembly into housing (20). The face
of the bearing race containing the part number must be out.
e. Slide lower bearing (14) over nut assembly (11), reposition any shims which were between the housing and
lower cover and install lower cover (9).
f.
Install top cover (8) on the housing.
g. After all bolts have been tightened, check the end play of the screw assembly. Add or remove shims between
housing (20) and lower cover (9) until there is a maximum end play of 0.004 inch and a minimum of 0.000 inch.
If necessary, use a press on the actuator to confine end play within the proper limits.
CAUTION: This adjustment is critical for proper operation of the actuator. It must be made with the pinion gear
removed.
h. Remove screw housing assembly (10) and nut assembly (11) from housing (20).
i.
Install bearing (19) on the pinion gear (17) with the “X” out and place the shaft in housing (20).
j.
Install bearing (18) and snap ring (16).
k.
Repeat Steps d. through g. Check the meshing of the screw housing assembly gear with the pinion gear to make
sure they rotate freely.
NOTE: If the P/N 50-810165 pinion gear is replaced by the P/N 50-810344 pinion gear on either Main gear actuator
of airplanes prior to LJ-116, the P/N 50-810172 (-1 LH or -2 RH) screw housing assembly must be replaced
by the P/N 50-810346 (-1 LH or -2 RH) screw housing assembly. The P/N 50-810172 housing is identified
by a yellow band on the base of the actuator housing encircling the nut assembly and the P/N 50-810346
housing is identifiable by a green band in the same relative location. On LJ-502 and after, the pinion gear
and the screw housing assembly is a gear set assembly and may not be replaced separately. Refer to the
applicable Illustrated Parts Catalog.
l.
Slide packing (7) and shield (6) over the nut assembly.
m. Install packing (5), washer (4) and shield retaining ring (3) over the shield.
n. Place the spring (2) over the clevis (1), insert the clevis into the nut assembly and install the retaining bolts.
o. Slide the grease seal (13) over the screw assembly (10) and press into place.
p. Fill the housing 1/2 full with grease (4, Chart 1, 91-00-00) and install plug (15).
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
Chart 2
Main Landing Gear Actuator Clevis Manufacturing and Wear Tolerances
NOTE
All dimensions are given in inches (Ref. Figure 3).
Item
I.D.
O.D.
Remarks
Actuator
Clevis Attach Holes (1)
Main Gear (Mechanical)
0.3135 to 0.3120
0.3150 maximum wear tolerance.
Clevis Attach Holes (1)
Main Gear (Hydraulic)
0.3125 to 0.3165
0.3265 maximum wear tolerance.
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
Main Landing Gear Actuator
Figure 3
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
Main Landing Gear Drag Brace (LJ-1 thru LJ-44)
Figure 4
MAIN LANDING GEAR ACTUATOR PROOF TEST AND BREAK-IN
NOTE: All loads are to be applied to the clevis (1) and in the direction of travel shown by the arrow in Figure 3.
a. Apply 700 ± 25 pounds tension load to the clevis. The pinion gear (17) should have backlash and must not bind.
b. Apply 400 ± 25 pounds tension load to the clevis. Run a minimum of 6 cycles through retraction and extension.
Cool the actuator for 5 minutes after each 3 cycles.
c.
Run a minimum of 3 cycles with 700 ± 25 pounds tension load. Again cool the actuator for 5 minutes after each
3 cycles. The actuator must not bind, squeal or bottom out with full travel.
MAIN LANDING GEAR DRAG BRACE - DISASSEMBLY
a. Remove the bushing (1) from the lower drag brace arm (6) (Ref. Figures 4, 5, and 6).
b. Remove the release link (2).
CAUTION: Each downlock hook is especially fitted for its position. If they are removed, they must be installed in
the same position.
c.
If necessary, remove the downlock hooks (4) from the upper drag brace arm (5).
d. Separate the upper (5) and lower (6) drag brace arms. Remove the bushing (7) from the upper drag brace arm.
e. The landing gear lock pin (8) should be removed only if it is to be replaced. It can be removed after the retaining
set screw and nut have been removed.
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
MAIN LANDING GEAR DRAG BRACE CLEANING AND PARTS REPLACEMENT
Clean all parts with solvent (6, Chart 1, 91-00-00). Inspect each drag brace arm for cracks, distortion and wear.
Charts 3 and 4 list manufacturing tolerances and wear limits to aid in determining the extent of wear. Replace all
damaged or excessively worn parts. If bushings are replaced, drill lubrication holes in them as required.
MAIN LANDING GEAR DRAG BRACE - ASSEMBLY
WARNING: To avoid damage to the airplane during maintenance place jacks under all three jack points (one
adjacent to the nose gear and one on each side of the fuselage on the aft spar, inboard of the
nacelle).
a. If the landing gear lock pin (8) required replacement, install the lock pin in the lower drag brace arm (6) with the
flat of the pin facing down for proper engagement of the downlock hooks on the flat of the pin. Secure the landing
gear lock pin In place with the set screw (Ref. Figures 4, 5, and 6).
b. Install the bushing (7) in the upper drag brace arm (5).
c.
Secure the upper drag brace arm (5) to the lower drag brace arm (6) with the retaining bolt, washer, nut and
cotter pin. Apply a light coat of grease (22, Chart 1, 91-00-00) to the bolt upon assembly.
CAUTION: Make sure that each downlock hook (4) is installed in the exact location from which it was removed to
ensure a proper fit.
d. Secure the downlock hooks (4) to the top of the upper drag brace arm (5) with the retaining bolt, washer and
nut. Apply a light coat of grease (22, Chart 1, 91-00-00) to the bolt prior to installation.
1. Tighten the retaining bolt for the downlock hooks until snug, then back off to the nearest castellation and
safety with the cotter pin.
NOTE: When the upper and lower arms of the drag brace assembly are engaged by the lock hook, there should
be a minimum clearance of 0.010 inch between the retaining face of each lock hook and the
corresponding landing gear lock pin and not more than 0.020 inch average clearance between the two
hooks and pins on the same drag brace.
e. Secure the release link (2) to the downlock hooks (4) with the retaining bolt, washer and nut. Apply a light coat
of grease (22, Chart 1, 91-00-00) upon installation. Tighten the retaining bolt until snug, then back off to the
nearest castellation and safety with the cotter pin.
f.
Lubricate the bushings with grease (22, Chart 1, 91-00-00).
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Chart 3
Main Landing Gear Drag Brace Manufacturing and Wear Tolerances
(LJ-1 thru LJ-1062; LW-1 and After)
NOTE
All dimensions are given in inches (Ref. Figures 4 and 5).
Item
I.D.
O.D.
Remarks
Drag Brace Assemblies (5, 6)
Bushing (1)
Bushing (11)
0.4975 to 0.4960 0.491 maximum wear tolerance. When the
upper and lower arms of the drag brace
assembly are engaged by the lock hook,
there should be a minimum clearance of
0.010 between the retaining face of each
lock hook and corresponding landing gear
lock pin and not more than 0.020 average
clearance between two hooks and pins on
the same drag brace. If more than the
above clearance exists, replace the pins or
hooks as required. the hook retaining face
may be filed to obtain the required
clearance.
0.5005 to 0.4995
Bushing (7)
Bushing (12)
0.505 maximum wear tolerance.
0.4995 to 0.4980 0.493 maximum wear tolerance.
0.6255 to 0.6245
Landing Gear Lock Pin (8)
Thickness of Flat
0.630 maximum wear tolerance.
0.317 to 0.312
0.300 maximum wear tolerance.
Distance between downlock
hook (4) surface and center of
0.3125 hole, perpendicular to
hook surface
2.656 to 2.646
2.680 maximum wear tolerance.
Slotted Hole (13, 15)
Length 0.687
Width
0.312 to 0.322
0.040 inch maximum wear limit of either the
length or the width dimension.
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Chart 4
Main Landing Gear Drag Brace Manufacturing and Wear Tolerances
(LJ-1063 and After)
NOTE
All dimensions are given in inches (Ref. Figure 6).
Item
I.D.
O.D.
Remarks
Drag Brace Assemblies (5, 6)
Bushing (1)
0.4975 to 0.4960 0.491 maximum wear tolerance. When the
upper and lower arms of the drag brace
assembly are engaged by the lock hook,
there should be a minimum clearance of
0.010 between the retaining face of each
lock hook and corresponding landing gear
lock pin and not more than 0.020 average
clearance between two hooks and pins on
the same drag brace. If more than the
above clearance exists, replace the pins or
hooks as required. the hook retaining face
may be filed to obtain the required
clearance.
Bushing (11)
0.5005 to 0.4995
Bushing (7)
0.505 maximum wear tolerance.
0.4995 to 0.4980 0.493 maximum wear tolerance.
Bushing (12)
0.6255 to 0.6245
Landing Gear Lock Pin (8)
Thickness of Flat
0.630 maximum wear tolerance.
0.317 to v 0.312 0.300 maximum wear tolerance.
Distance between downlock
hook (4) surface and center of
0.3125 hole, perpendicular to
hook surface
2.656 to 2.646
2.680 maximum wear tolerance.
Slotted Hole (13, 15)
Length 0.687
Width
0.312 to 0.322
0.040 inch maximum wear limit of either the
length or the width dimension.
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Main Landing Gear Drag Brace (LJ-45 thru LJ-1062; LW-1 and After)
Figure 5
Main Landing Gear Drag Brace (LJ-1063 and After)
Figure 6
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MAIN LANDING GEAR TORQUE KNEE INSPECTION
a. Pull the landing gear control circuit breaker.
b. Place a note on the circuit breaker panel which identifies that landing gear Maintenance and/or rigging is in
progress.
c.
Remove all power from the airplane and disconnect the battery.
d. Place the airplane on jacks. Raise jacks to a height sufficient only to support the weight of the airplane. Do not
raise the tires off the floor. Having tires in contact with the floor will prevent the Main landing gear lower pistons
from extending after the torque knees are removed.
e. Deflate the main gear shock strut.
f.
Remove the upper torque knee from the airplane. Refer to Chapter 32-10-00 in the King Air 90 Series
Maintenance Manual.
g. Inspect the upper torque knee for cracks, On airplanes with aluminum upper torque knees, refer to the
ALUMINUM TORQUE KNEE FLUORESCENT PENETRANT INSPECTION, If the airplane has been retrofitted
with steel upper torque knees, refer to STEEL TORQUE KNEE MAGNETIC PARTICLE INSPECTION. Pay
particular attention to the areas referenced in Figure 7. Replace torque knee when crack Indications are found.
h. If no indications of cracks are found, apply chemical conversion coating (35, Chart 1, 91-00-00), epoxy
polyamide primer (20, Chart 1, 91-00-00) and urethane topcoat paint (39, Chart 1, 91-00-00) to restore the
torque knee to its original finish condition. Refer to Chapter 20-08-00 in the King Air 90 Series Maintenance
Manual.
i.
Remove the lower torque knee from the airplane. Refer to Chapter 32-10-00 in the King Air 90 Series
Maintenance Manual.
j.
Inspect the lower torque knee for cracks. Refer to STEEL TORQUE KNEE MAGNETIC PARTICLE
INSPECTION. Pay particular attention to the areas pointed out in Figure 8. Replace the torque knee when crack
indications are found.
k.
If no indications of cracks are found, apply chemical conversion coating (35, Chart 1, 91-00-00), epoxy
polyamide primer (20, Chart 1, 91-00-00) and urethane topcoat paint (39, Chart 1, 91-00-00) to restore the
torque knee to its original finish condition. Refer to Chapter 20-08-00 in the King Air 90 Series Maintenance
Manual.
l.
Install the inspected upper and lower torque knees or new torque knees. Refer to Chapter 32-10-00 in the King
Air 90 Series Maintenance Manual.
m. Remove the airplane from jacks.
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CAUTION: Never tow or taxi with a flat strut. Even brief towing or taxiing with a deflated strut can cause severe
damage.
Do not inflate the struts while the airplane is on jacks since sudden extension or over-inflating of the
struts may bend the torque knees.
Before removing the airplane from the jacks, make sure that the manual hand pump handle is in the
stowed position, the red knob on the service valve is pushed down and the plunger retainer and safety
pin or safety wire are installed, the landing gear control handle is in the down position and the landing
gear is down and locked.
With the airplane empty except for fuel and oil, inflate the main strut with dry filtered air or nitrogen only
until the piston is extended 3 inches.
n. Service the shock strut.
o. Place the airplane on jacks.
NOTE: While rigging the landing gear, observe the components and hydraulic lines for any indications of binding,
interference, leakage or questionable operation. Correct any problems as necessary.
p. Perform a landing gear system rigging and retraction check. Verify safety switch rigging. Refer to Chapter
32-30-00 (Mechanical Landing Gear) or Chapter 32-31-00 (Hydraulic Landing Gear) in the King Air 90 Series
Maintenance Manual.
q. Return the airplane to service.
ALUMINUM TORQUE KNEE FLUORESCENT PENETRANT INSPECTION
NOTE: Only qualified personnel shall perform nondestructive inspections.
a. Remove the bushings from the three lug locations on the torque knee.
b. Clean any grease, film or lubricant residue from the torque knee with solvent (6, Chart 1, 91-00-00).
NOTE: Follow paint stripper manufacturer’s instructions and recommendations for use of the product.
c.
Remove all paint and primer from the surface of the torque knee with liquid paint stripper (32, Chart 1, 91-00-00).
d. After completing paint stripping, thoroughly wash the torque knee in a warm water cleaning solution of detergent
(36, Chart 1, 91-00-00) or equivalent mixed at a concentration of 1 ounce of detergent cleaning solution per
gallon of warm water. Scrub the torque knee with the solution using a non-metallic bristle brush.
e. After cleaning, rinse the torque knee in hot running tap water to remove residual cleaner. Hand dry with a clean
cloth (40, Chart 1, 91-00-00).
f.
Perform a chemical etch of the torque knee. Chemical etching will increase the capability to detect cracking in
locations where surface smearing or abrasion has occurred. Additionally, chemical etching will assist in
removing active corrosion on the surface of the part. Refer to CHEMICAL ETCHING procedure.
g. Perform a Type I, Method C, Sensitivity Level 3 fluorescent penetrant inspection in accordance with
ASTME-1417 and MIL-STD-6866 on all surfaces of the torque knee except the inner shear web. The following
considerations associated with the inspection process should be observed:
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1. Allow a minimum penetrant dwell time of 30 minutes. Excessive dwell times should be avoided because
some penetrants exhibit a tendency to dry during prolonged exposure to air. All surfaces of the part should
be Maintained wet with penetrant during the dwell cycle.
2. Indications detected during fluorescent penetrant inspection should be confirmed or disproved. A
questionable indication should first be dry sanded with 180 grit aluminum oxide abrasive paper (38, Chart
1, 91-00-00), sanding in a direction perpendicular to the direction of the indication. The local area should
then be recleaned with penetrant system cleaner (37, Chart 1, 91-00-00) and reinspected, starting with
application of penetrant.
3. Indications confirmed to be representative of cracking are cause for rejection of the part unless engineering
authorization will allow removal of material to eliminate the cracking location.
h. Coat torque knee with chemical conversion coating (35, Chart 1, 91-00-00). Allow the coating to dwell for
approximately five minutes. After dwell time has elapsed, wash the coated areas with water and blow dry (do
not wipe dry).
i.
Prime and paint each torque knee using epoxy polyamide primer (20, Chart 1, 91-00-00) and a urethane topcoat
paint (39, Chart 1, 91-00-00).
STEEL TORQUE KNEE MAGNETIC PARTICLE INSPECTION
The magnetic particle inspection for the torque knee consists of a wet continuous, fluorescent particle technique
using a pulse length of 1/2 to 1 second. Three phase full wave direct current, half wave direct current, or alternating
current may be used and accomplished as follows:
NOTE: Only qualified personnel shall perform nondestructive inspections.
Do not remove bushing from torque knee.
a. Clean any grease, film or lubricant residue from the torque knee with solvent (6, Chart 1, 91-00-00).
CAUTION: Do not remove the cadmium plating during paint removal.
NOTE: Follow paint stripper manufacturer’s instructions and recommendations for use of the product.
b. Remove paint and primer from the surface of torque knee with liquid paint stripper (32, Chart 1, 91-00-00).
c.
After paint stripping, thoroughly wash the torque knee in a warm water cleaning solution of detergent
(36, Chart 1, 91-00-00) or equivalent mixed at a concentration of 1 ounce of detergent cleaning solution per
gallon of warm water. Scrub the torque knee with the solution using a non-metallic bristle brush.
d. After cleaning, rinse the torque knee in hot running tap water to remove residual cleaner. Hand dry with a clean
cloth (40, Chart 1, 91-00-00).
NOTE: Inspect the torque knee for any evidence of cracks after each shot.
e. Shot #1 - Shoot a centrally located central conductor through the small holes at the small end of the torque knee
at 500 amps.
f.
Shot #2 - Shoot a centrally located central conductor through the large holes at the larger end of the torque knee
at 600 amps.
g. Demagnetize the torque knee.
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h. Shot # 3 - Shoot a direct contact shot between the left-hand large diameter hole ear and the right-hand small
diameter ear at 600 amps.
i.
Demagnetize the torque knee.
j.
Shot # 4 - Shoot a direct contact shot between the right-hand large diameter hole ear and the left-hand small
diameter ear at 600 amps.
k.
Shot #5 - Shoot a coil shot at 800 amps with the torque knee located near the inside diameter of the coil. On
this coil shot, use a 5 turn coil or 4,000 amp/turns if 5 turn coil is not used.
l.
Demagnetize and clean the torque knee.
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KING AIR SERIES COMPONENT MAINTENANCE MANUAL
POTENTIAL
CRACK
LOCATIONS
POTENTIAL
CRACK
LOCATIONS
BB32N
983386AA.AI
Main Landing Gear Upper Torque Knee Inspection Areas
Figure 7
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POTENTIAL
CRACK LOCATIONS
(LOWER SURFACE)
POTENTIAL
CRACK LOCATIONS
BB32N
983387AA.AI
Main Landing Gear Lower Torque Knee Inspection Areas
Figure 8
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CHEMICAL ETCHING
WARNING: Sodium hydroxide and sodium hydroxide solutions should be handled with care using suitable
personal safety protection equipment. Avoid contact with eyes, skin or respiratory tract.
When preparing acid solutions, always add acid to water, never add water to acid. Acid
solutions should be handled with care using suitable personal safety protection equipment.
Avoid contact with eyes, skin and respiratory tract which can cause severe chemical burns and
possible permanent damage. Make sure work areas are adequately ventilated or use a mask or
suitable breathing equipment.
a. In a polyethylene container of suitable size, prepare a 10% (Weight/Volume) solution of sodium hydroxide (34,
Chart 1, 91-00-00) by slowly adding 100 grams of sodium hydroxide (NaOH) to 90 milliliters of water. Stir gently
until the sodium hydroxide has dissolved. Dilute solution to a final volume of 1 liter and allow to cool before use
(70 - 90° F).
b. Prepare a 30% solution of nitric acid (33, Chart 1, 91-00-00) by adding concentrated nitric acid slowly to 70
milliliters of water while stirring until a total volume of 1,000 milliliters (1 liter) is obtained.
NOTE: The etch rate of the sodium hydroxide solution is influenced by the concentration, temperature of solution
and the extent of etchant depletion. Recommended times for immersion in the solution are based on etch
rates established for the recommended concentration used within the recommended temperature range. A
one liter container of solution is considered acceptable for etching six torque knees before the solution
depletion will significantly affect etch rates. After etching six torque knees, the solution should be disposed
of in accordance with local regulations.
c.
Immerse torque knee in the sodium hydroxide solution for 2 to 3 minutes. During etching of the torque knee,
Maintain the sodium hydroxide solution at a temperature between 70 - 90° F. The solution temperature may be
controlled by positioning the container in a sink or larger vessel and flowing hot or cold tap water, as required,
around the solution container.
d. After completion of the required immersion time, remove the torque knee from the sodium hydroxide solution
and rinse in warm flowing tap water.
e. Immerse the torque knee in the nitric acid solution for one to five minutes or until all black smut is removed. The
solution will remove smut created during the etch process and brighten the surface.
f.
Remove the torque knee from the nitric acid solution and thoroughly rinse in warm, flowing tap water for
complete removal of the solution.
CAUTION: Do not overheat the torque knees during drying, overheating may cause precipitation aging of the alloy
and result in loss of strength.
g. The torque knee must be thoroughly dried to drive moisture out of any possible cracks prior to performing the
liquid fluorescent penetrant inspection. Drying should be accomplished by heating the part to a temperature of
150 - 200° F for a minimum of one hour. Heating can be accomplished in an oven or the use of heat lamps.
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UPPER SHOCK ABSORBER INSPECTION
Perform a Fluorescent Liquid Penetrant Inspection on the upper shock absorber as follows:
NOTE: For the Fluorescent Liquid Penetrant Inspection, refer to Chapter 20-00-00 in the Beechcraft Corporation
Structure Inspection and Repair Manual (P/N 98-39006B or subsequent).
a. Apply fluorescent liquid penetrant below the drag link attach collar and above the torque knee attach collar.
b. Inspect the upper shock absorber for cracks. Pay particular attention to the areas referenced in Figure 9.
Replace the upper shock absorber when crack indications are found.
c.
If no indications of cracks are found, remove the penetrant with a clean cloth slightly dampened with the
penetrant system cleaner.
d. Return the airplane to service.
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Main Landing Gear Upper Shock Absorber Inspection Areas
Figure 9
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