Gyro Legacy

Late Gov. Carnahans legacy includes gyro system inspections, maybe an AD


The following information is derived from the FAAs Service Difficulty Reports and Aviation Maintenance Alerts.


The FAA has issued a Special Airworthiness Information Bulletin that warns of possible AD action requiring gyro backups for IFR flight.

The SAIB cautions pilots to conduct a condition check of the vacuum or pressure system prior to each IFR flight.

Last falls crash of a Cessna 335 carrying Missouri Gov. Mel Carnahan prompted a review of service difficulty reports of vacuum system components. In the past 27 years, mechanics have filed 2,003 reports – 18 in the 12 months prior to the bulletin.

Parker Hannifin (Airborne) has acknowledged a potential latent failure of its check valves that could lead to a dual vacuum or pressure system failure.

The FAA recommends a vacuum/pressure system check prior to each flight in IFR operations, or installation of a backup attitude indicator. A backup attitude indicator should have an independent power source, should be capable of operating for 30 minutes after an electrical failure and should be in the pilots scan.

The FAA ends its SAIB with a bit of foreshadowing: The FAA is considering several options, including rulemaking action, to mandate these recommendations.

Beech C23 Sundowner
Deteriorated Flexible Plumbing

During an annual inspection, the technician discovered that most of the flexible fluid lines installed in the aircraft were stiff and deteriorated.Two of the brake lines were chafing on the firewall and were leaking. All the flexible lines installed in this aircraft appeared to be original equipment and were more than 30 years old.

Beech B24R Sierra
Flap Cable Damage

While conducting an annual inspection, the technician discovered a wing flap cable was frayed.The flap cable had several broken cable strands at one location. The technician determined the cable contacted a screw head when the flaps were in the fully retracted position.

Beech 35C33 Debonair
Empennage Cracks

During a 100-hour inspection, the technician found several cracks in the empennage structure.The cracks were located in the doubler, the right skin section and the aft bulkhead. There were two cracks in the doubler with the same origin.Part total time – 7,584 hours.

Cessna 172R Skyhawk
Defective Cowling Mounts

An FAA Certified Repair Station that operates a fleet of 16 like aircraft reported that technicians often find one or more defective cowling shock mounts. Since February 2000, this operator has replaced 85 cowling mounts. The defects usually involve rubber tearing or separating from the mounting plate. When the 172 was reintroduced, the cowling mounts were changed to a thinner design than previously used.

Cessna 172RG Cutlass
Landing Gear Failure

During a check ride, the right main landing gear failed to extend. The pilot reached out the entry door and physically pulled the gear into the locked position. The technician discovered the splined section of the landing gear pivot was twisted and separated from the remainder of the pivot. Cessna Service Bulletin 90-1 offers an improved pivot assembly, which was complied with about three years earlier. Since this incident, the FAA has issued AD 2001-06-06, which also deals with the landing gear pivot problem. Part total time – 2,800 hours.

Cessna 182 Skylane
Insufficient Elevator Travel

While conducting a scheduled inspection, the inspector discovered the elevator up travel was insufficient.The elevator traveled 19 degrees up, however the airplanes type certificate requires 25 degrees up travel. The technician discovered a bolt in the control column was striking a directional gyro unit that had been installed in 1993. The aircraft owner said it was difficult to land the airplane well.

Cessna 182Q Skylane
Wing Flap Damage

During a postflight inspection, a technician found a long tear in the left wing flap skin.The upper flap skin was broken a distance of approximately 10.25 inches at the trailing edge. Also the upper and lower flap skins were cracked around several of the trailing edge fasteners outside the broken section. The exact cause of the damage could not be determined but may have been due to the flaps being deployed at excessive airspeeds. Part total time – 2,401 hours.

Cessna T206H Turbo Stationair
Oil Hose Damage

During the first scheduled inspection since this aircraft was new, a technician found the turbocharger oil hose damaged.The hose assembly had been routed next to an engine exhaust system component and was severely burned and leaking. Failure of the oil hose would have caused loss of engine oil and possibly engine failure.Part total time – 110 hours.

Cessna 414A Chancellor
Aileron Anomaly

While conducting an inspection, the technician noticed the right aileron was not streamlined with the trailing edge of the wing.The outboard end of the aileron was approximately 0.25 inch high when the inboard end was even with the trailing edge of the wing. After further inspection, the technician discovered the outboard aileron hinge bracket was an incorrect part for this installation. The part number indicated was for the left aileron.The aircraft maintenance records revealed the incorrect hinge bracket was installed during a previous wing repair. The incorrect part was installed due to an error in the manufacturers parts catalog.

Diamond DA-20-A1 Katana
Nose Landing Gear Cracks

During a preflight inspection, the pilot found the nose landing gear fork cracked.Both sides of the nosewheel fork were cracked through approximately 75 percent of their width. The cracks were obscured by paint and the wheel pant installation. The damage could have been caused by a hard landing or a nosewheel-first landing.Aircraft total time – 1,195 hours.

Grumman American AA-5A Cheetah
Wing Structural Damage

While performing other maintenance on the left wing fuel tank, the technician found a buckled wing rib.The owner said the aircraft had suffered previous damage when an insect nest plugged the left wing fuel tank vent. The insect nest was cleaned out, but it was evident there had been no effort to evaluate the damage. This aircraft has been operating approximately 7 years since the previous damage occurred.Part total time – 4,247 hours.

Piper PA-24 Comanche
Engine Exhaust Stack Broken

During a flight, the pilot experienced a complete loss of engine power and made an off-airport landing.The technician discovered the right rear engine exhaust stack was broken inside the carburetor heat muff, allowing hot exhaust gases into the engine compartment. As a result, the insulation melted on the P-lead wires, shorting them and causing the engine to fail.Aircraft total time – 4,053 hours.

Piper PA-31-350 Chieftain
Alternator Failure

The pilot reported the left engine alternator warning light illuminated. A technician discovered the positive battery lug was loose. The loose lug allowed the terminal to short to the case ground, causing the battery cable insulation to melt. He replaced the alternator and battery cable. Part total time – 54 hours.

Piper PA-46-350 Malibu
Landing Gear Actuator Defect

The right main landing gear did not indicate down-and-locked when the pilot selected the down position. After conducting aerial maneuvers designed to lock the gear, a down-and-locked indication was attained.A technician checked the right main gear actuator and adjusted the down-and-locked switch in accordance with the proper technical data. The landing gear functioned correctly but the problem recurred on the next flight.The technician suspects there is a problem with the servicing information contained in the technical data, which contributes to this problem. Part total time – 1,270 hours.

Textron Lycoming O-320
Faulty Cylinder Security

The technician discovered three broken hold-down studs on the No. 1 cylinder. All but two of the remaining hold-down stud nuts had backed off the threads. The cylinder was in danger of separating from the engine case. He discovered the hold-down stud nuts on both engines were below the required torque value.

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