Untorqued, Delaminated

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


Boeing A75N1 Stearman

Broken Engine Mount Bolts

Inspection of a recent engine installation uncovered a fractured engine-mount bolt. After informing the STC holder of the failure, we were told we should have re-torqued these bolts after 25 hours of operation. This information was not included in the STC. The submitter believes the STC is inadequate in ensuring continued airworthiness.

Part Total Time: 100.0 hours.

Cessna 170B

Failed Tailwheel Assembly

During an annual inspection, all parts inside the tailwheel unit were found extremely worn. Additionally, the tailwheel axle had been damaged and its end was partially ground off,


extending through the cotter-pin hole used to secure the nut on the end of the axle. The entire Scott 3200 tailwheel assembly was replaced with a serviceable unit.

Part Total Time: (unknown)

Cessna 182S

Cracked Battery Mount Structure

Both aircraft battery-shelf support brackets were found cracked in their forward and aft ends (four cracks total). Each crack started at the end of the support in the 90-degree bend radius, propagating toward the center of the part. This is the fourth 182S/T model we have found to be cracked in this manner, each requiring replacement supports (p/n 0712059-1). One previously repaired aircraft has already cracked the replacement parts.

Part Total Time: (unknown)

Cessna Corvalis 300/350/400 Models

Failed Empennage Structure

Four reports dating back to 2006 detail structural damage to the empennage after extreme braking. Extensive structural damage-including gaps in the structure and de-bonding of the composite fuselage-have been identified. These extreme braking maneuvers consist of prolonged periods of heavy braking and tire skidding, resulting in large oscillatory motions known as “gear walk.” Cessna reportedly is developing an advisory to communicate information about the proper use of brakes as noted in the POH.

Part Total Time: (various)

Diamond DA40

Failed Alternate Air Control Valve

A shop maintaining a fleet of 20 Diamond DA-40s is finding the alternate air valve body control cable (p/n DAI-9076-00-04) loose or completely disconnected. When reinstalling the cable, they find stripped threads on the alternate air valve body. This problem has now occurred on 14 different aircraft at between 147 and 350 hours TIS.

Part Total Time: (various)


Please enter your comment!
Please enter your name here