The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.
The FAA has issued a special airworthiness information bulletin in a continuing attempt to get owners of Beech prop airplanes to use proper gust lock procedures.
Numerous incidents and accidents have resulted from the failure of a pilot to remove the flight control gust lock prior to attempting to take off. Many involved the use of a makeshift gust lock, including such things as a common bolt or nail inserted through the holes in the control column provided by the manufacturer.
Obviously, this tactic did not provide the pilot with any kind of reminder that a gust lock was engaged. Raytheon and Beech have issued service bulletins to modify the flight control columns such that a gust lock could only be engaged in the nose down and/or roll input position. Beech airplanes manufactured prior to 1971 had control locks that would lock the controls in the neutral position, thus allowing takeoff with the locks engaged.
Regardless of the configuration of the gust lock, proper adherence to the required preflight inspection and preflight checks specified in the AFM would have prevented all of these accidents.
The FAA is again recommending owners use only gust locks that provide an unmistakable warning to the pilot that a gust lock is engaged.
American General AA-1 Clipper
Defective Engine Exhaust System
While conducting an annual inspection, the technician discovered the engine exhaust system was cracked.There were numerous spider web cracks at the junction of the tail pipe and the muffler can. The cracks were adjacent to a weldment that attaches the two components. In addition, a large welded repair was previously installed at the same location.Part total time – 2,330 hours.
Beech F33 Bonanza
Wheel Brake Discrepancy
The pilot returned before takeoff and reported the right wheel brake would fail intermittently, causing loss of aircraft directional control.A technician discovered the right brake master cylinder was causing intermittent pressure to the right wheel brake. The master cylinder poppet valve was sticking occasionally, causing loss of brake pressure and aircraft directional control.Part total time – 40 hours.
Beech F33A Bonanza
Turbocharger Tube Damage
During an annual inspection, the technician discovered the turbocharger crossover tube was damaged. It appeared the crossover tube was damaged when it contacted the air-conditioner system drive pulley.This aircraft had been modified by the installation of Turbo Flight STC SA5223NM and SA5222NM. The technician speculated the damage was the result of the tube being purposefully deformed during installation to provide clearance between the tube and the air-conditioner drive pulley.The technician obtained a new replacement tube and was instructed to deform it to gain clearance, which the technician refused to do.Part total time – 316 hours.
Beech N35 Bonanza
Nose Gear Steering Defect
During an annual inspection, the technician discovered defective hardware in the nose gear steering system.The nose gear steering yoke assembly bolt was bent and very difficult to remove. The bolt was cracked at the bend radius and in danger of breaking.The damage may have occurred when the ground movement personnel exceeded the turn limits while moving the aircraft. He stated this was the second similar defect he has found recently.Part total time – 5,040 hours.
Beech S35 Bonanza
The owner reported the alternator was inoperative.The technician noticed the cotter key, nut and washer used to secure the clutch assembly were missing.The clutch assembly was broken and the alternator shaft was severely worn. He discovered the interior of the alternator was soaked with oil. He removed the engine oil pan and found some of the missing hardware.It appeared the alternator front bearing failed due to extreme wear, allowing looseness of the shaft. The shaft looseness caused movement, the cotter key and nut broke, and the washer migrated out of place.Part total time since overhaul – 340 hours.
Beech 95-B55 Baron
During a scheduled inspection, the technician noticed several small cracks in the baggage compartment door area.The technician removed the baggage compartment floor and discovered severe corrosion on several structural members. The insulation/sound-proofing material used on the underside of the floor panels was wet. The submitter suggested Raytheon issued a service bulletin to address the corrosion problem in this as well as other areas of the aircraft. Part total time – 3,108 hours.
Engine Starter Anomaly
While preparing for a flight, the engine starter engaged when the pilot turned on the master switch.A technician discovered the engine starter contactor points were welded together. This condition supplied electrical power to the engine starter when the master switch was closed.Part total time – 47 hours.
Cessna 172N Skyhawk
Defective Wheel Brakes
During a scheduled inspection, the inspector discovered the right wheel brake linings were severely cracked and broken.A technician discovered the brake lining attachment rivets were loose and had not been properly installed. The rivets were not swelled sufficiently, and it appeared they were installed without using the correct tool. He disassembled the left main wheel and found similar defects.
Cessna 172P Skyhawk
Aileron Control System Failure
While investigating an accident, an FAA inspector discovered the aileron control system had failed.The inspector found the right aileron cable was severed. There was evidence of severe corrosion at the point where the cable separated, as well as other locations. The cable separated adjacent to a pulley in the cabin overhead area, which is covered by the headliner. The cable strands were very brittle, and several cable strands were broken prior to the separation.
Cessna 172R Skyhawk
Wing Flap Discrepancy
While accomplishing Cessna SB 00-57-01, the technician discovered a discrepancy on the left wing flap support arm.The inboard bearing support arm on the inboard flap track was severely gouged and worn. The damaged area matched the outer radius of the roller assembly. The inner roller bearing cage of the roller assembly was offset enough to allow the outside diameter of the assembly to rotate against the flap support arm. The inner bearing cage offset was approximately .025 inch, which matched the support arm gouge depth.Part total time – 933 hours.
Globe Swift GC-1B
Landing Gear Collapse
The pilot stated that the right main gear collapsed during landing rollout.A technician discovered that a Woodruff key in the gear actuator was sheared. He could not determine if the key sheared before or after the gear collapse. There are three possible causes for this defect:Many aircraft owners have modified their aircraft by installing a different hydraulic pump and increasing the output pressure adjustment, purportedly to speed the landing gear cycle time. During landing gear extension with increased hydraulic pressure, sufficient force is applied against the Woodruff key that may cause it to shear.It is also possible that the Woodruff key installed in this case was soft and not a properly hardened AN key. Considering the location of the cockpit controls, it is possible that the pilot inadvertently moved the landing gear switch in the up direction while reaching for the wing flap switch. When the gear switch is then placed back in the down position, the hydraulic system pressure is opposed by the aircraft weight, which generates enough force to cause the Woodruff key to shear.Part total time – 1,390 hours.
Piper PA-18-135 Super Cub
During a refurbishment project, a technician found exceptionally severe corrosion on the fuselage structure.This aircraft is equipped with observation windows that have horizontal aft window channels approximately 3 feet long. The submitter believes the channels collected water and other contaminates and routed them aft to a major upper longeron tube cluster, where corrosion developed and consumed the structure.The fuselage had to be scrapped due to the extent and severity of the corrosion damage.Aircraft total time – 3,700+ hours.
Piper PA-28-181 Archer
Pitot Static System Defect
While conducting a 24-month test of the pitot/static system, a technician discovered a massive leak.The pitot system would not hold any pressure. He discovered both hoses that connect the aluminum tubing to the pitot static system probe were split and severely deteriorated.This aircraft was operated in a salt-air environment, but it is not known if that factor contributed to the demise of the hoses.Part total time – 481 hours.
Piper PA-28-181 Archer
Flight Control Cable Damage
During a scheduled inspection, the technician discovered the flight control cables were severely damaged.Both the left and right stabilator control cables were severely frayed and worn. The damage was located at fuselage station 128.7.The submitter believes substandard cables installed by the manufacturer caused this damage. The submitters conclusion was supported by 10 additional entries in the FAA Service Difficulty Program database. The 10 additional reports included Piper Models PA-44-180 and PA-28-161 that use the same part number stabilator cable. Also, there was one report involving a Piper Model PA-28R-201, which uses a different control cable that only varies in length.Part total time – 2,342 hours.
Piper PA-31-350 Chieftain
Nose Landing Gear Structural Defect
During a scheduled inspection, the technician discovered the upper nose landing gear actuator attachment support bracket was severely cracked. The technician submitted three additional reports on aircraft that were very similar. The defect may have been the result of age or a high number of gear cycles and operating hours. Indeed, all four reports were on high-time aircraft.Part total time – 22,328 hours.
Piper PA-32R-300 Lance
Defective Nose Landing Gear Door
A technician submitted 12 reports concerning nose landing gear door structural failures.All the failures occurred on the right nose gear door brace. In each case, the door brace broke at the rear attachment point. The technician discovered several cracks adjacent to the attaching rivets.The failures happened between 54 and 1,076 operating hours on each part.