Cracked, Loose, Failed

During slow-flight maneuvers, the instructor noticed the green, landing gear "safe" light was not illuminated. The student observed the left gear was hanging out-and swinging. The gear was cycled, but the left main remained free and disconnected. The instructor elected to retract the right and nose gears and land gear-up. Maintenance found the left gear pivot had sheared at the spline shaft. The right gear was removed and Zyglo checked. Close inspection found the right pivot was cracked three-quarters of the circumference around the spline shaft, nearing complete failure. Gear pivot p/n: 22411143.

Editorial Staff

Friday, May 22, 2009 at 12:00 AM ET

Verified

Mementos of an early pursuit of flight. Courtesy Gregg Maryniak

Key Takeaways:

Multiple aircraft experienced landing gear system failures, including a Cessna R182 with a sheared main gear pivot (and the other cracked), and Piper PA32R-301T aircraft with main gear down-lock switch wires fraying due to tension.
Engine performance problems were reported across different aircraft: a Piper PA-31-350's electric fuel boost pump failed due to a dislodged bypass valve, and a Continental IO-470-VO engine suffered piston skirt breakage, possibly exacerbated by cold weather starts.

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Cessna R182

Sheared Main Gear Pivot

During slow-flight maneuvers, the instructor noticed the green, landing gear “safe” light was not illuminated. The student observed the left gear was hanging out-and swinging. The gear was cycled, but the left main remained free and disconnected. The instructor elected to retract the right and nose gears and land gear-up.

Maintenance found the left gear pivot had sheared at the spline shaft. The right gear was removed and Zyglo checked. Close inspection found the right pivot was cracked three-quarters of the circumference around the spline shaft, nearing complete failure. Gear pivot p/n: 22411143.

Part Total Time: 4754.0 hours.

Piper PA-31-350 Failed Electric Fuel Pump

The pilot reported substantial power loss from the left engine just after takeoff, and that the left low-pressure fuel boost pump light was illuminated. A technician could not find any problems with the engine during run-up other than the electric,

low-pressure fuel boost pump (intended for flight above 15,000 feet MSL) not supplying rated pressure. After a second takeoff attempt revealed a similar power loss, the pump was removed, revealing the bypass valve assembly had dislodged from the pump body and acted as a flow restrictor. Parker Hannifin p/n 2B6-64. Time since overhaul: 2098.4 hours.

Part Total Time: (unknown).

Piper PA32R-301T Failing Main Gear Down-Lock Switch

The main gear down-lock switch wires installed on several identical aircraft pull tight on the strut during retraction, pulling wire strands apart. The silicone insulation tends to hold the wire ends together, creating intermittent contact. Wire p/n: 153-615; switch p/n not provided.

Part Total Time: 399.8 hours (average).

Continental IO-470-VO Broken Piston Skirt

A Cessna 310s left engine exhibited low oil pressure. A significant amount of metal was found in the oil filter. The engine torn down and chunks of piston skirting was found in the oil pan. The number 2 piston had come apart at the skirting around the bottom ring-land below the piston pin, and the number 1 piston was found to be cracked in the same area where piston 2 was broken. A possible contributing factor may have been starting the engine at a temperature near 0 degrees F. Piston p/n: AEC648029.

Part Total Time: 933.4 hours.