The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts. Click here to view “Airworthiness Directives.”
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As the result of a fatal stall/spin accident in Canada, the FAA is issuing Airworthiness Alert 2720 for Cessna 150/152s manufactured after 1966. In July 1998, a Cessna 152 with a student and flight instructor failed to recover from an intentional spin. A 150/152 should recover from a spin by simply releasing the flight controls.
Examination of the wreckage showed the rudder jammed past its normal travel limit.
A 50-hour inspection was completed the day before the accident. During the check the right pedal rudder bar return spring and its lever arm were found broken. The broken pieces were removed and not replaced. No reference to this outstanding defect was recorded in the aircrafts log book.
After examining other 152s (swept-tail 150s have the same rudder control system), investigators found it possible to jam the rudder past its normal travel limit when the rudder horn stop plate is forced aft of the stop bolt head. The forward edge of the stop plate then becomes lodged under the head of the stop bolt, causing the rudder to jam in an over-travel position. This will prevent spin recovery.
The rudder control system includes right and left pedal rudder bar return springs to maintain tension on the rudder cables. Accident investigators believe that the combination of the missing rudder pedal return spring combined with a full rudder pedal input by the pilot caused the rudder to jam beyond the normal rudder travel stop limit.
Cessna is looking at design changes to the rudder stops. Meanwhile FAA Airworthiness Alert 2720 advises operators of the importance of maintaining the integrity of the rudder control system.
The Airworthiness Alert advises technicians to pay special attention to the following important items.
• The condition of the rudder structure, e.g. no damage or distortion, especially in the area of the rudder horn attachment.
• The condition of the rudder horn. Several rudder horns have been found bent or distorted. This prevents the stop plate from squarely contacting the stop bolt head and allows the stop plate to contact the side of the tailcone above and below the stop bolts.
• The condition of the rudder pedals and associated torque tubes and verify free movement of the pedals. The accident aircraft showed signs of rudder cable attachment bolt interference with the adjoining aileron cable pulley.
• The condition of the rudder horn stop plate. The stop plate should contact the stop bolt head squarely.
• Verify rigging of the rudder control system including the adjustment of rudder travel stop bolt, rudder cable length and proper nose wheel steering tube (bungee) length.
All of these items contributed to this fatal accident. -John Lowery
Aero Commander 114B
Engine Exhaust Chafing
During an annual inspection, the technician noticed an engine exhaust stack was chafing on an engine mount. The exhaust stack chafed the engine mount tube that connects the right lower engine mount bracket at the firewall to the right nose gear trunnion mount. The tube was worn to a depth of .035 inch. An exhaust stack clamp was missing, but the spring and bracket for the clamp were intact. Part total time – 298 hours.
Beech A36 Bonanza
Flight Control Column Discrepancy
During a scheduled inspection, the technician noticed the pilots control column felt sloppy. Investigating further, the technician found the rivets used to secure the forward collar to the control yoke tube were severely worn and working.The technician replaced the defective rivets with rivets that are one size larger to obtain a proper fit. Failure of these fasteners could completely disable the aileron and elevator flight control systems and create a very serious hazard to flight safety. There are four rivets used for the forward collar and eight rivets for the aft collar. The manufacturer says the four rivets on the forward collar are sufficient to secure the forward collar.Part total time – 2,300 hours.
Beech 58P Baron
Defective Oxygen Bottle Security
While conducting other maintenance, the technician discovered the 15-cubic-foot oxygen bottle was not securely mounted to a shelf in the empennage. The oxygen bottle is normally secured by two metal bands routed through the mount brackets. The forward bracket was broken, and the aft bracket had one of its two legs broken.An unsecured oxygen bottle creates a hazardous situation, due to the possibility of interference with aircraft systems and because a sudden release of oxygen pressure could propel the bottle as a missile.
Beech A90 King Air
Defective Elevator Trim System
The flight crew reported severe vibration from the empennage during a descent for landing. Investigation revealed a bolt and bushing missing from the right elevator trim tab horn. The elevator electric trim servo lower bearing was displaced from the housing; therefore, the servo drum and shaft wobbled during rotation. Also, the trim cable was tangled around the servo drum.Part total time – 1,452 hours.
Beech 90 King Air
Defective Cabin Heater
The pilot reported the cabin heater operated only on the ground or when the landing gear was extended in flight. Maintenance personnel discovered the Janitrol A10D40 heater combustion liner had several cracks. The combustion air safety switch tested within limits but did not function properly every time. The cracks presented the possibility of carbon monoxide being introduced into the cockpit/cabin. This unit is not covered by any AD that would require a periodic pressure-decay test.
Beech A200C King Air
Defective Firewall Fuel Shutoff Valve
The aircraft was brought to maintenance due to erratic annunciator indications for the No. 1 engine firewall shutoff valve. The technician found the shutoff valve switch housing was broken. The switch had been previously removed and had been reinstalled using a longer screw. The extra screw length allowed the shank end to penetrate the switch housing, resulting in debris that caused intermittent and erratic annunciator indications.
Cessna 170
Defective Wing Flap Cable
During an annual inspection, the inspector discovered a damaged right wing flap cable. The flap cable was severely frayed approximately one-half inch from the clevis fitting attachment. The damage may have been the result of wind moving the flap and flexing the cable at the damaged area. Since this aircraft was manufactured in 1948, age was probably also a factor. Part total time – 4,117 hours.
Cessna 182S Skylane
Engine Oil Loss
After completing a 20-minute flight, the pilot noticed engine oil on the lower fuselage. Approximately 7.5 quarts of oil was lost from the total supply of 9 quarts.A maintenance technician discovered the engine oil pressure switch was broken where the plastic housing is mounted on the engine. The incident occurred prior to AD 2000-04-01, which requires replacement of the oil pressure switch with an improved part.Part total time – 1,005 hours.
Cessna U206G Stationair
Engine Fuel Leak
During an annual inspection, the inspector discovered an engine compartment fuel supply hose leaking profusely. When the technician turned on the electric fuel boost pump, fuel leaked from the braided, crimped area of the hose near the end. AD 71-24-04 covers the subject of fuel hose leakage but does not apply to this particular aircraft. The AD references Cessna Service Letter 71-7, Supplement 1, which applies to all single-engine aircraft equipped with flexible fluid hoses.
Cessna 207A Stationair
Defective Nose Gear Steering Part
After the technician installed a new nose gear steering bungee assembly sprocket, the drive chain came off during an operational test. The technician reinstalled the chain and conducted another test while observing the chain travel on the sprocket gear. The chain rode normally for approximately two-thirds of a revolution then began riding up on the top of the sprocket teeth and disengaged from the sprocket. The technician found some of the sprocket teeth were not symmetrical and were cut differently from the others.Part total time – 0 hours.
Defective Hardware
A shop purchased a quantity of self-locking castellated shear nuts directly from Cessna. While repairing a flight control system, the technician noticed the chamfer on one of the nuts was so deep that only one gripping thread remained. He checked the remaining nuts in stock, and discovered 37 out of 75 were bad.
EAM Life Preserver KSE-35HC2l8
Defective Inflater Assembly
While the technician was attempting to inflate a dual cell adult life preserver, both toggles were pulled simultaneously. This occurred during a test of the emergency equipment in a repair shop. The back cell inflated correctly; however, the front cell failed to inflate. The front cell failure was due to the actuating lever pulling out of the Henco inflater assembly housing. This allowed the inflater pin and spring to fall out of the assembly without breaking the CO cartridge seal. The technician disassembled both inflater assemblies and a comparison of the two actuating arm steel retainer pins revealed the front cell pin was approximately .092 inch shorter than the back cell pin. This life preserver is not affected by EAM Service Bulletin SBV-25-2.
Piper PA-23-250 Aztec
Electrical System Failure
While preparing for an annual inspection, the technician was unable to apply battery power to the aircraft. The mechanic found the interior of the battery contactor consumed by corrosion, causing total failure of the electrical system. The damage may have been caused by corrosion (propagated by moisture and other contaminates) entering the unit, loose or worn electrical contacts, and the extended period of time the aircraft remained in the hangar. Part total time – 1,795 hours.
Piper PA-24-250 Comanche
Wing Attachment Fasteners Broken
While installing avionics equipment, the technician discovered several broken fasteners in a wing attachment fitting. Twelve rivets were broken and missing from the right rear wing attachment fitting at fuselage station 136. Further inspection revealed the technician could move the right wing trailing edge up and down using hand pressure. He checked the other three wing attachment fittings and found them in good condition. The damage may have been caused by hard landings. The aircraft had been involved in two previous accidents, and it is possible damage went undetected during repairs. The FAA Service Difficulty Reporting program database contains two additional entries of similar failures.Part total time – 3,017 hours.
Piper PA-30 Twin Comanche
Fuel Odor in the Cockpit
The flight crew reported a strong fuel odor in the cockpit during flight. The technician discovered the heater fuel shutoff valve was leaking. The fuel traveled down the forward bulkhead in the nose section then aft into the landing gear transmission compartment. Part total time – 850 hours.
Piper PA-34-220T Seneca
Propeller Spinner Bulkhead Cracks
During a scheduled inspection, the technician found cracks in the propeller spinner bulkhead. The cracks were located at or adjacent to each of the attachment bolt holes. There were no dynamic balance weights attached to the bulkhead.Part total time – 288 hours.
Piper PA-44-180 Seminole
Flight Control Skin Crack
During a scheduled inspection, the inspector discovered a crack in the aileron skin. The right aileron inboard skin panel was cracked on the top side near the aft edge and 12 inches from the inboard end. This is a new aileron as called for in Piper Service Bulletin 1016. Part total time – 438 hours.
Rotax 912F
Improper Engine Maintenance
During an accident investigation involving a Diamond Model DA20-A1 aircraft, the NTSB discovered the Rotax 912F engine had been maintained in accordance with practices common to general aviation engines such as the Teledyne Continental O-200, instead of the requirements specified in the Rotax engine maintenance manual. The engine has a very small piston-to-cylinder wall clearance and it operates a geared propeller with a slip clutch. The unique features of the Rotax engine require close adherence to the requirements outlined in the Rotax engine maintenance manual. Rotax and other manufacturers build many different engine models which are used in amateur-built aircraft and experimental aircraft. There is no regulatory requirement dictating the maintenance practices for these engines; however, these engines have very specific manufacturers maintenance technical data. For this reason, proper training and adherence to the manufacturers technical data are highly recommended. Engine total time – 1,297 hours.
Textron Lycoming O-235
Excessive Internal Wear
During an annual inspection of a Cessna 152, the technician changed the engine oil and filter. When he opened the oil filter, he found aluminum metal shavings. A laboratory analysis determined the shavings originated from the piston pin plugs. The technician removed all four cylinders and found severe pitting at the lowest point of piston travel on each cylinder wall, as well as piston pin plug wear. Part total time – 466 hours.
