September 1999 FAA AC 43-16A 5 Beech; Model V35A; Bonanza; Defective Oil Temperature Sending Unit; ATA 7720 The engine installed in this aircraft was a Teledyne Continental, Model IO-520B.
While investigating the cause of inaccurate engine oil temperature indications, technicians discovered a defective temperature sending unit. The maintenance records indicated this was the original sending unit installed when the aircraft was new.
The technician ordered and received a replacement sending unit. He conducted a receiving inspection, and discovered the replacement sending unit’s wire stud was loose and could easily be rotated by “finger pressure.” He rejected the replacement sending unit and contacted the vendor.
The vendor checked his stock and rejected four other sending units before finding a sending unit that did not have loose wire studs and threaded studs. He compared one of the new sending units to the original sending unit and discovered the stud on the original sending unit was tight and did not allow any movement. The vendor stated the crimping or staking process used to install the stud during manufacture may be deficient. A loose wire stud presents a problem when the wire is installed because there is no acceptable way to prevent the stud from rotating while the nut is tightened.
The submitter suggested that the manufacturer’s engineering staff evaluate the new sending units for adherence to the original design specifications. He also stated the original sending unit (P/N 1512926) listed in the Beech Parts Manual has been superseded.
Part total time-4,000 hours.
Beech; Model B90; King Air; Faulty Electrical Wiring; ATA 2450 After operating the air-conditioning system during a phase inspection, the technician smelled and saw smoke in the cockpit.
The technician investigated and discovered a wire (P/N P83A2) smoldering under the center cockpit pedestal at the isolation limiter bus. There are two wires (P/N’s P83A2 and P83B2) at this location. The wires are aluminum and run from the right wing starter relay bus to the isolation limiters in the cockpit. Except for the emergency bus, these wires provide electrical power to the entire aircraft without circuit protection. While removing the wires for replacement, one wire (P/N P83B2) broke at the starter relay. The wire was severely corroded and the insulation displayed evidence of excessive heat damage.
The aluminum wires were installed in Models 65-90 and 90-Series King Air aircraft through serial number LJ 440.
The submitter stated, “The old wires are dangerous and must be replaced.”
Part total time-10,007 hours.
Beech; Model B99; Airliner; Entrance Door Cracks; ATA 5210 The flightcrew reported that the pilot’s crew door was very difficult to close.
A technician lubricated and inspected the door latch mechanism. While inspecting the door hinges, he discovered a cracked upper forward hinge (P/N 99-420024-7). The 1-inch long crack ran along the hinge line.
The submitter speculated that the hinge crack was caused by flexing the door structure due to excessive seal thickness.
Part total time not reported.
FAA AC 43-16A September 1999 6 Beech; Model BE99; Airliner; Defective Main Landing Gear Torque Knee; ATA 3213 During a scheduled inspection, the technician discovered a crack in the left main landing gear torque knee.
Both the upper and lower torque knee (P/N 50-810323-7) halves were cracked near the center pivot bolt which connects the upper and lower halves. The cracks had progressed to the point where pivot bolt loss was imminent.
The submitter stated that hard landings, landing gear sideloads, and other factors may have contributed to this failure.
Part total time not reported.
Beech; Model B100; King Air; Defective Engine Starting Electrical Circuit; ATA 3260 The pilot reported that the left engine starter would not engage.
Maintenance technicians discovered a defective left main landing gear “squat” switch (P/N 444EN49-6). The “squat” switch contacts interrupted the engine start control circuit by not supplying electrical power to the start relay control box. The location of the landing gear “squat” switch makes it vulnerable to contamination, corrosion, and failure.
The submitter recommended that the “squat” switch receive frequent inspections.
Part total time-6,618 hours.
Beech; Model BE200; King Air; Interior Light Fixture Failure; ATA 3320 During flight, smoke filled the aircraft cabin.
The pilot evacuated the smoke and made a safe landing.
Maintenance personnel discovered the source of the smoke was a cabin light assembly (P/N 00741626) ballast. The ballast shorted, generated smoke, produced extreme heat, and distorted a nearby plastic window molding.
The submitter stated, “The heat intensity could easily have caused a fire and may have ended in a catastrophic accident.”
Part total time not reported.
Beech; Model 400A; Beechjet; Landing Gear System Failure; ATA 3230 The pilot reported that the 2-amp landing gear circuit breaker opened when the landing gear was selected to the “up” position. He placed the landing gear selector to the “down” position, and made a safe landing.
The technician discovered that two wires on the gear selector control switch were crushed and shorted together in the area of the cockpit center pedestal structure. The wires were repaired and rerouted to provide adequate clearance.
The submitter suggested closely inspecting this area at every opportunity.
Part total time-1,277 hours.
CESSNA Cessna; Model 172N (C172); Skyhawk;
Carburetor Problem; ATA 7322 On the first flight of the day, the student pilot reported the engine would not idle cutoff.
When he shut off the engine using the magneto switch, the propeller ran backwards.
The instructor stated the aircraft did not idle properly the previous evening; however, he assumed hot weather caused the problem.
A technician examined the engine and discovered the carburetor’s (P/N 10-5009) upper and lower body halves had separated approximately 0.125 inch. Evidently, the carburetor overhaul facility technician did not torque the bolts properly before he set each bolt’s lock-washer tab.
September 1999 FAA AC 43-16A 7 The submitter stated this is the third occurrence of the same problem involving three separate overhaul facilities.
Part time since overhaul-25 hours.
Cessna; Model 172RG (C72R); Cutlass RG;
Faulty Risistor; ATA 2460 During an annual inspection, the technician noticed smoke emanating from the radio rack.
An investigation disclosed the resistor (P/N S2041-50-16) for the cigarette lighter was damaged and smoking. He found burn marks on both sides of the glovebox side wall where the resistor is affixed. The nylon portion of the affixing locknut was completely melted. The ceramic insulator at the base of the cigarette lighter (P/N 0513052-20) was broken. He noted the 7-amp fuse and the 10-amp circuit breaker were not activated.
The submitter stated that the replacement parts contain a new-type lighter assembly (P/N 0513039-7) and an additional circuit breaker (P/N 60232-1). He recommended issuing an Airworthiness Directive (AD) requiring the installation of a second circuit breaker.
Part total time-3,315 hours.
Cessna; Model 172 (C172); Skyhawk; Airbox Part Missing; ATA 7160 During the first Phase I inspection, the technician discovered a part missing from the airbox assembly (P/N 0550364-7). There was a gap around the alternate air door where the part belonged.
Also, apparently due to the door hinge’s misalignment, filler material was used to fix a gap in the air inlet door assembly. Most of the filler material broke away leaving a ½-inch gap in the assembly. The remaining filler material displayed cracks.
The submitter replaced the airbox.
Part total time-50 hours.
Cessna; Model 172S (C172); Cutlass;
Misaligned Rudder Pedals; ATA 2720 This new aircraft had less than 100 hours of total operating time. During the first Phase II inspection, the technician noticed the rudder pedals on both pilot stations were not matching in their alignment.
The technician discovered the left station’s pedals had its mounting arm (P/N 0411307-0), on the right pedal, drilled incorrectly at the point where it attached to the crossover shaft.
At the point where the right station’s pedals attached to the crossover shaft, the left pedal was also drilled incorrectly.
The technician notified the manufacturer of this misalignment problem. The manufacturer sent parts that were properly drilled.
Part total time-97 hours.
Cessna; Model 172S (C172); Cutlass; Pilot Seat Support Problem; ATA 2510 When the pilot’s seat back was selected in the full-upright position, it was approximately 3 inches back and toward the reclined position.
The submitter discovered the seat back support fitting (P/N 0514215-8) was bent. He noted that this was the second fitting replaced on the same seat. The first fitting was replaced after only 23.6 hours of use. This is the fourth failure of the same part within his fleet of new Cessna aircraft.
The submitter stated past accident statistics show that a seat part failure, especially during a takeoff roll, may have grave consequences.
It is important for new owner/operators to be aware of the problem prior to a disaster.
Part total time-51 hours.
Cessna; Model 172S (C172); Cutlass; Skin Crack on Flap; ATA 5753 While performing a Phase I inspection, the technician noticed a crack at the trailing edge of the left flap assembly. The crack was located
FAA AC 43-16A September 1999 8 on the lower surface. It started at the fourth rivet from the inboard edge of the flap and migrated outboard for approximately 2 feet.
After the submitter notified the manufacturer of this defect, he received a new assembly.
Part total time-149 hours.
Cessna; Model 172S (C172); Skyhawk; Fuel Leak; ATA 7322 During the first Phase I inspection, the technician noticed the presence of fuel in the vicinity of the air inlet.
An investigation revealed that the specific point of fuel leakage occurred at the air inlet elbow (P/N 0550362-3) leading to the fuel control unit. A more extensive search disclosed that the overboard drain adapter, which is riveted to the air inlet elbow, was not properly sealed. The improper seal was not readily visible.
Part total time-50 hours.
Cessna; Model 310 (C310); Cessna 310; Worn Fuel Selector; ATA 2823 During an extensive aircraft inspection, the technician discovered that both fuel selector torque tube assemblies (P/N 0820000-5 and 0812000-13) were severely worn.
Tube (P/N 0820000-5) was worn at the fuselage grommet area, and tube (P/N 0812000-13) was worn at the bulkhead at Fuselage Station (FS) 557.5. The tube damage was only detectable because the tubes were removed.
Under normal inspection procedures, this defect may have gone undetected. The extent of the damage was approximately 65 percent to the perimeter of the tube and approximately 50 percent through the tube wall thickness.
The submitter stated owners with similar make and model aircraft, should remove the four shielded bearing blocks and inspect this area as soon as possible.
Part total time not reported.
Cessna; Model 402B (C402); Businessliner;
Fuel Blockage; ATA 2822 The pilot reported that he was unable to prime the right engine.
A technician discovered the right boost pump was producing inadequate pressure. He opened the fuel tank to remove and replace the boost pump and discovered a 2-½ inch square data tag (P/N 1C6-10) was unglued and resting directly below the pump’s fuel pickup tube. When the pump was activated in the priming process, the data plate was sucked up against the tube inlet, and the fuel flow was reduced to less than 10 pounds per square inch.
The submitter recommends that pumps with this type of data tag be replaced with the type of tag that is more permanently affixed.
Part total time-193 hours.
Cessna; Model 421C; Golden Eagle III;
Hydraulic Leak; ATA 2916 The maintenance department received a work order that indicated hydraulic fluid was visible in the nose compartment.
The technician discovered a hydraulic leak emanating from the reservoir. The fluid leak occurred at both ends of the sight tube (P/N 5117007-12) at the attach points. The technician discovered the same problem on a similar aircraft.
Due to the low failure time, the submitter stated this problem indicates a production flaw. The submitter cautions all owners and operators of similar aircraft to inspect for this problem. A complete failure of this tube would result in loss of the entire hydraulic supply.
Part total time-50 hours.
September 1999 FAA AC 43-16A 9
DIAMOND Diamond; Model DA20-C1; Propeller Attachment Bolt Failure; ATA 6111 The pilot reported that during an after-takeoff climb, a severe vibration occurred. He made a safe landing and summoned maintenance technicians.
The technician discovered the propeller spinner was cracked. After removing the propeller spinner, he discovered five of the six propeller mount bolts broken. It appeared the bolts failed due to shear stress. He sent the bolts to the manufacturer for inspection and evaluation.
The submitter stated the bolt attachment holes in the propeller flange were elongated which indicates the bolts were not torqued to the specified value.
Part total time-40 hours.
GRUMMAN AMERICAN Grumman American; Model AA5B; Tiger;
Defective Aileron Skin; ATA 5751 During an annual inspection and compliance with Airworthiness Directive (AD) 79-22-04, the technician discovered the left aileron skin was delaminated.
The upper aileron skin (P/N 5202035-516) delamination varied from 1 to 4 inches where the leading edge skin was bonded to the rib.
It was necessary to remove and replace the aileron.
The submitter stated that this area deserves extra attention during inspections and maintenance.
Part total time-1,675 hours.
LAKE Lake; Model LA4-200; Buccaneer; Loss of Engine Power; ATA 7160 This aircraft incorporated a Textron Lycoming, Model IO-360-A1B, engine which was modified by Supplemental Type Certificate (STC) SA2990WE. This STC allowed the installation of an engine turbocharger.
The pilot reported that with the throttle full open and the waste gate closed, the engine had excessively low boost.
The technician conducted an investigation and several contributing discrepancies were given credit for the engine power loss. The boost air inlet fitting weld, located at the bottom of the induction airbox, was cracked all the way around the circumference. This allowed some boost air to escape overboard. The welded attachment fittings between the airbox and the fuel injection control were cracked. He found numerous cracks in the airbox extending from various points of the circumferential weld. The airbox flapper valve hinge pins and hinge pin mounts were excessively worn and on the verge of complete failure. The rubber elbow that attaches the boost duct to the airbox assembly had a large rip and allowed the loss of more boost air. Some areas of the elbow were wrapped with “electrical tape” to cover worn places.
The submitter speculated that these defects combined to degrade engine performance. The weld cracking was credited to normal vibration and previously accomplished “unairworthy” weld repairs. Thorough and timely inspections, as well as proper repair techniques, should prevent these types of defects.
Part total time not reported.
FAA AC 43-16A September 1999 10 PIPER Piper; Model PA28-151 (P28A); Cherokee; You Say Your Head Was Where?; ATA 7322 After a landing, a fire started in the engine cowling.
The technician discovered the carburetor air-intake hose (P/N 99849-03) from the air filter was connected to the muffler. It should have been connected to the carburetor airbox.
(I bet that robbed a bit of horsepower!) The cabin heat duct was connected to the carburetor airbox.
These erroneous connections may have led to a backfire which ignited a leaking primer fuel flex line.
We’d hate to think of what would happen if this plane had a toilet to flush. People, lets stay tuned-in and pay attention out there.
Part total time unknown.
Piper; Model PA28-161 (P28A); Warrior II;
Broken Landing Gear Trunnion; ATA 3211 While on a training flight, after a touch-and-go landing, the instructor felt a severe vibration.
He landed the aircraft without personal injuries; however, the aircraft sustained damage to the right wing, the flap assembly, and the stabilator.
Observers on the ground reported that something was hanging from the right wing.
An inspection revealed the right main landing gear trunnion (P/N 65319-004) broke at the upper torque link attach ears. With the trunnion broken, only the brake hose held the lower strut and wheel assembly to the aircraft.
The submitter stated that he reviewed the maintenance records for this 1982 aircraft and found no entries of landing gear trunnion replacement. Apparently, this part was original on an aircraft used exclusively in flight school operations.
Part total time-9,478 hours.
Piper; Model PA28-180; Archer; Spar Cap Damage; ATA 5711 During an annual inspection, the technician found evidence of fretting at the left and right main landing gear legs (P/N’s 35644-04 and 35644-05) where they attach to the wing’s lower spar cap.
The technician also discovered the lower attach bolts (AN4-11A) were not properly torqued, and the attach point bolt holes were elongated on both the gear legs and the spar caps. This allowed a wearing motion between the gear legs and the spar caps.
The submitter states that the spar damage was caused by the improperly torqued bolts which caused the wearing motion between the parts.
He recommends checking bolts for proper torque during 100-hour inspections and annual inspections.
Part total time-4,040 hours.
Piper; Model PA28R-200 (PA28R); Arrow 200;
Alignment Cam; ATA 3211 After takeoff, the pilot could not retract the nose gear. He made a safe landing even though he experienced steering difficulty throughout the landing roll and taxi.
The technician discovered that the steering alignment cam was outside and to the left of its guide bracket (P/N 67107-00). This caused the cam to hit the bracket’s ear, thus, not allowing the landing gear to fully extend. Also, because the tire was not aligned it would not fully retract into the cowling. (Refer to the following illustration.)
The submitter stated that because of normally high torque throughout the takeoff roll, the pilot’s excessive right rudder application may cause the alignment cam to strike the ear on the alignment bracket during gear retraction.
The resulting bracket flex caused it to strike the trunnion housing, and the cam assembly came out of its track.
The submitter states the manufacturer has already welded a stiffener across the ear
September 1999 FAA AC 43-16A 11 assembly. However, he recommends that the manufacturer make the base plate thicker to avoid the excessive flexing caused by right rudder application throughout the gear retraction.
Part total time not reported.
Piper; Model PA28R-210T (P28B); Turbo Dakota; Inoperative Landing Gear; ATA 2400 A small fire erupted in the right side of the engine compartment, and smoke entered the cockpit area. The electrical power to the gear down switch was interrupted which rendered it inoperative.
The technician noticed that the fire probably started at a point approximately 1 inch below a small bundle of wires leading to the nose gear switch. The insulation on the wires was brittle and cracked possibly due to the fire.
However, it is more likely that the insulation on the wires was brittle and cracked before the fire. Due to the defective insulation, the wires contacted each other, caused a short, and started the fire.
Piper; Model PA28R-210T (P28B); Turbo Dakota; Missing Bypass Valve; ATA 8120 In the past, an unknown technician installed a turbo heat blanket on this aircraft. At that time, the technician failed to reinstall the exhaust bypass valve pipe (P/N STC SA 4731 NM).
The submitter stated the bypass valve is designed to direct hot exhaust gases to the proper area. Without the bypass valve, hot exhaust gas blew directly onto the electrical wiring bundle attached to the landing gear switches.
Part total time-4,442 hours.
Piper; Model PA31-350 (PA31); Chieftain; Gear Door Actuator Problem; ATA 3232 After takeoff, the pilot routinely selected the gear handle to the “up” position; however, the red “gear unsafe” light remained illuminated.
He hand pumped the gear down and made a safe landing.
The technician inspected the landing gear system and discovered that the right main inner gear door actuator (P/N 2114-1) up line fitting (P/N 458-910 and AN837-4D) had snapped in half.
The submitter stated that during gear inspections, extra vigilance should be paid to ensure that tire and brake parts do not entangle hydraulic lines.
Part total time unknown.
Piper; Model PA32RT-300T (P32T); Turbo Lance II; Corrosion; ATA 5540 While complying with Airworthiness Directive (AD) 79-26-04 and Piper Aircraft Service Letter 882A, the technician removed the rudder. He noticed the attach bolts to the
FAA AC 43-16A September 1999 12 lower rudder fitting (P/N 38394-02) were approximately 40 percent corroded. Water standing in the rudder’s lower attach tube may have caused the corrosion. (Refer to the following illustration.)
The submitter stated that if the tube had adequate drain holes, water would not stand in the rudder’s lower attach tube.
Part total time-2,605 hours.
Piper; Model PA34-200 (PA34); Seneca; Nose Gear Failure; ATA 3230 The submitter stated the nose gear on this aircraft failed due to excessive play in the “overcenter linkage.” The excess play was caused by a bent clevis bolt (P/N 400692) which was installed through the downlock link assembly (P/N 95329-00) and the “overcenter linkage.” He suspected that the clevis bolt was bent during a hard landing.
The submitter stated that this make and model aircraft is prone to nose gear failure. He stated the manufacturer should re-engineer the nose gear or, at least, install a larger clevis bolt.
Part total time-67 hours.
Piper; Model PA44 (PA44); Seminole; Propeller Stop Problem; ATA 6114 The plastic stop plate assembly (P/N 78213-00) was broken at the bottom of each side, directly beneath the propeller control levers.
The technician discovered the parts were only held in place by the assembly spring. These plates normally pivot up and out when the propeller levers are placed in the feathered position. The left plate had worked its way to a point under the right throttle lever which could have restricted the throttle ’s travel to the most-aft position.
The submitter recommends that the manufacturer either construct the plates from a more substantial material or design a hinge or pivot where fatigue is most likely to occur.
Part total time-482 hours.
HELICOPTERS BELL Bell; Model UH-1; Huey; Fuel Solenoid Failure;
ATA 7321 Information for the following article was taken from a report submitted by the Royal Australian Air Force.
During a flight test, fuel leakage was discovered in the engine compartment.
A fuel solenoid valve (P/N 79247) was recently replaced, and it was the source of the leak. The fuel solenoid valve is a part of the fuel pressure regulator which is installed on the engine turbine accessory section.
The fuel leak originated at the fuel solenoid valve end cap which had become displaced. Also, seals inside the solenoid valve were severely deteriorated. A bit of research through the military part records indicated this pressure regulator was at
September 1999 FAA AC 43-16A 13 least 30 years old before being installed.
(This is a good reason for seal deterioration.) This part came through a military supply system which is not entirely different from the commercial supply system. Since shelf life is so important, manufacturers, distributors, and dealers should keep accurate records concerning part history. Also, maintenance technicians need to be aware of this problem and use all means possible to determine the age and condition of aviation parts prior to installation.
Thanks to our “mates down-under” for their support of the FAA’s Service Difficulty Program.
Part time since overhaul-209 hours.
Bell; Model 206L-1, -3, and -4; Long Ranger;
ATA 5500 The FAA continues to receive reports of cracks developing in the tail boom structure. The similarity of the reported defects led to the issuance of FAA Airworthiness Directive (AD) 99-02-01, dated January 6, 1999.
AD 99-02-01 is referenced in Bell Alert Service Bulletin 206l-98-114, dated November 25, 1998.
Several articles have been written in this publication and other aviation publications concerning this subject. Compliance with AD 99-02-01 is critical to flight safety. If cracks are discovered, the tail boom must be replaced. Refer to AD 99-02-01 for specific serial number applicability, requirements, and instructions for compliance. (The following illustration shows the area where cracks are typically found.)
All owners, operators, or maintenance entities are strongly urged to comply with AD 99-02-01 as soon as possible.
Part total time is not applicable.
Bell; Model 222; Wiring Damage; ATA 3400 The pilot reported the autopilot altitude functions were inoperative.
An investigation disclosed that the insulation on several “Kapton” wires was dissolved. The area of damage occurred where the wires pass under the fuel pump and vent area. The technician determined the wire insulation damage was caused by fuel leakage. If not detected and corrected, this condition may cause a fire. The submitter recommended inspecting this area for damaged wire insulation.
Part total time not reported.
FAA AC 43-16A September 1999 14
ENSTROM Enstrom; Model 280C; Shark; Improper Alternator Installation; ATA 2421 During the first flight following the installation of a new alternator (P/N ALX 8421), the pilot reported the alternator failed and there was a severe engine oil leak.
The technician could not determine the circumstances surrounding the alternator installation. He discovered that this unit was installed without removing the cooling fan assembly as directed by the manufacturer’s maintenance manual. Evidently, the cooling fan was damaged when the new alternator was installed. Consequently, the alternator cooling fan “threw” a blade which punctured the oil cooler.
The submitter stated this problem may affect all Enstrom piston engine helicopters.
He suggested that the manufacturer issue a service bulletin detailing an inspection procedure for cooling fan damage and improper alternator installations. Proper use of technical data should prevent this type of defect and enhance flight safety.
Part total time not reported.
EUROCOPTER Eurocopter; Model AS350-B2; Ecureuil;
Electrical System Failure; ATA 2400 During a tour flight with passengers aboard, the aircraft lost electrical power. The pilot made a safe, emergency landing at a nearby heliport.
The pilot told the technician that only the “fuel pump” light illuminated on the “caution panel.” The technician applied external electrical power and discovered that all the lights, radios, gauges, and the air-conditioning system operated normally. When he depressed the start switch, the starter did not rotate.
He also discovered the starter/generator (P/N 150SG122Q) had failed. After he installed a new starter/generator , the operational test was satisfactory. He disassembled and inspected the failed starter/generator . The inspection revealed that two of the four brushes were so badly worn that the spring could not keep them in contact with the commutator. The commutator and six other brushes were also burned.
The submitter reported that it had been 68 operating hours since the starter/generator brushes were inspected. The maintenance records indicated the starter/generator brushes were serviceable at that time.
Part total time-437 hours.
MBB MBB; Model BK-117B1; Tail Cone Crack;
ATA 5500 During a scheduled inspection, the technician found a crack on the left forward tail cone splice.
The crack originated from a relief hole at the intersection of the lower tail cone splice (P/N 117-22132-01) bend radius, traveled up, and terminated at the next bend radius. The submitter speculated that the lower bend radius relief hole was not “deburred” during manufacture which caused concentrated stress points and resulted in this defect. The splice plate is constructed of 7075-T6 aluminum which makes it susceptible to stress cracking.
The submitter believes that dressing the bend radius edges and relief holes may eliminate this type of defect.
Part total time not reported.
September 1999 FAA AC 43-16A 15
ROBINSON Robinson; Model R-22; Beta; Improper Magneto Assembly; ATA 7414 A technician installed a factory-rebuilt engine and during the initial operational test, there was no RPM indication.
The technician traced the problem to the right magneto which he removed. Inside the magneto (Bendix/TCM P/N S4LN-204), he found that the tachometer points (P/N ES10-361631) had been improperly installed. The exact circumstances, assembly, and condition of the magneto points was not described by the submitter. The maintenance records indicated that the magneto had been overhauled and assembled by a repair station without performing a bench test of the unit. It is wise to conduct a thorough receiving inspection on new parts, used parts, and/or overhauled parts prior to installation.
Part total time-0 hours.
SIKORSKY Sikorsky; Model S76A; Structural Corrosion;
ATA 5313 This report stated that four like helicopters had similar structural corrosion defects at the same locations.
During an inspection, the technician found severe corrosion between the left and right upper engine longerons and the outer skin panels. The damage was located at fuselage stations (FS) 250 to FS 300. This area is almost inaccessible and diligence is required to conduct a proper inspection. Severe corrosion was also found in the tail boom at FS 300 to FS 336 and in the area where the vertical fin attaches to the tail boom. All of the corrosion areas displayed exfoliation and an advanced state of metal penetration.
The submitter urged all operators of like helicopters to conduct a rigorous inspection of these areas as soon as possible.
Part total time not reported.
AGRICULTURAL AIRCRAFT AYRES Ayres; Model S-2R; Bull Thrush; Engine Power Loss; ATA 8120 While conducting spraying operations, the engine lost power requiring an emergency off-airport landing.
The engine used in this aircraft was a PZL, Model PZL-35. During an investigation, the technician determined the engine operated but would not develop normal manifold pressure. After further investigation, he discovered the turbocharger seal was “blown.”
The submitter did not mention the age of the seal; however, he indicated it was severely worn.
Part total time-1,775 hours.
AMATEUR, EXPERIMENTAL,
AND SPORT AIRCRAFT EXTRA Extra; Model EA-200; Fuel Leak; ATA 2810 During flight, the pilot smelled and saw fuel in the cockpit. He made an immediate and uneventful landing.
An investigation disclosed the fuel hose (P/N PC-01786) connecting the filler neck to the main fuselage tank was not attached. The hose separated from the top of the tank flange
FAA AC 43-16A September 1999 16 and allowed fuel to enter the cockpit. The hose was not long enough to allow for the airframe flexing during operational conditions.
The submitter suggested that all operators and builders check the factory-supplied fuel hose for adequate length.
Part total time not reported.
POWERPLANTS AND
PROPELLERS
ALLIED SIGNAL (TEXTRON
LYCOMING) Allied Signal; Model LTS 101-650-B1; Idler Gear Failure; ATA 7200 This engine was used in an MBB, BK-117 helicopter. While disassembling the engine, the technician found metal particles in the bottom of the gear box assembly.
Further inspection revealed the idler gear (P/N 4-081-350-08) was missing one of the attachment bolts. Three other nuts were damaged and/or missing pieces. The technician checked the torque value on the remaining bolts and discovered they were all loose.
The submitter recommended checking the torque value of the idler gear bolts at 1,200 operating hour intervals. He also suggested replacing loose nuts (P/N MS21043-5) and bolts (P/N 4-081-119-04).
Engine total time-2,944 hours.
TELEDYNE CONTINENTAL Textron Lycoming; Model O-320-E2A; Improper Parts; ATA 8530 While conducting an engine compression check during an annual inspection the number 3 cylinder indicated “0” compression.
The cylinder (P/N 05K21237-A) was leaking past the exhaust valve. When the technician removed the exhaust system he found the exhaust valve guide split. He removed the cylinder and sent it to a repair station for overhaul. After receiving the cylinder, a repair station representative called the submitter to verify that this cylinder was new when it was installed. The maintenance records indicated all four cylinders were purchased new through a Textron Lycoming vendor. The four cylinders were installed as a set and received no further maintenance since the engine was assembled.
The repair station discovered the piston (P/N 75413-P-10) in the faulty cylinder was .001 inch oversized. The three remaining cylinders were also oversized, and all of the cylinders were worn beyond the maximum limit. A manufacturer’s representative indicated it was impossible to install .001 inch oversized pistons into a standard cylinder.
Here is another case where “Murphy’s Law” prevailed. The submitter did state that it was “a very snug fit.”
The aircraft owner now has four scrap cylinders and metal contamination throughout the engine. The submitter speculated the installing technician did not check part number applicability or measure the pistons prior to installation. The cylinder assemblies were original equipment manufacturer (OEM) produced and were delivered in May 1992. Is it possible that the cylinder packaging was “mis-marked?”
The submitter suggested that anyone who acquired new cylinder assemblies through a vendor or the OEM consider checking part number applicability. This engine was installed in a Piper, Model PA 28-140 aircraft and was in operation 7 years before this occurrence.
Part total time-801 hours.