Cracked And Corroded

A casting crack was found visually during the course of an annual inspection. The crack is located on the forward end of the support casting (p/n 07416031), starting 0.25 inches from the outboard mount holes and ends within 0.25 inches of the mount holes on the inboard side of the casting.

Editorial Staff

Thursday, July 19, 2012 at 12:00 AM ET

Verified

NAFI board chair-elect Karen Kalishek helped the owner of this Piper M350 with initial M350 training and also brought the airplane back to KGRB with him from Vero Beach, Florida. Courtesy Karen Kalishek

Key Takeaways:

Multiple reports detail cracks in critical structural components, including main landing gear attach castings, inertial vane shafts, and aileron pulley brackets, often discovered during annual inspections.
Severe corrosion was found on a Cessna 208B rudder torque tube in an inaccessible area, prompting a recommendation for an engineered inspection hole to prevent hidden damage.
An alternator brush failure in a Cessna T206H, characterized by intermittent circuit breaker trips and complete disintegration of a field brush, highlights component wear issues, especially with manufacturer-exclusive parts.

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Cessna 182G Skylane

Cracked MLG Attach Casting

Part Total Time: 2690.0 hours

Cessna 208B Grand Caravan

Cracked Inertial Vane Shaft

On investigating a bypass door squawk, the technician discovered the shaft on the forward inertial vane assembly (p/n 200803511002) was cracked. The mechanic also noticed the inlet splitter (p/n 200803511002) was cracked at its two ends and one attach angle was broken.

Part Total Time: 140.0 hours

Cessna 208B Grand Caravan

Rudder Torque Tube Corrosion

This Hawaii-based aircraft’s rudder torque tube (p/n 263066-3) was scheduled for replacement due to elongated holes in the bell crank. Once the rudder and skin were removed, severe corrosion was found on the upper part of the torque tube in an area not visible during any scheduled maintenance. The corrosion had reached the stage of “blistered rust” and the “L” angle on one side was easily separated with minor force. By design, the rudder is not sealed on the top. The submitter suggests a rudder inspection hole be engineered so maintenance can easily inspect the torque tube for corrosion.

Part Total Time: 12,563.6 hours

Piper PA-28R-200 Arrow II

Cracked Aileron Pulley Brackets

During an annual inspection, both the l/h and r/h lower support aileron pulley brackets (p/n: 67550000) were found to be cracked in the forward inboard radius mount flange at each wing rib. A piece of one of these pulley brackets was detached.

Part Total Time: (unknown)

Cessna T206H Turbo Stationair

Alternator Brush Failure

The alternator field circuit breaker tripped intermittently over the previous 25 flight hours, causing various instances of radio noise. The alternator (p/n 99105923) remained functional. Upon replacing the original alternator, it was disassembled and the ground brush found to be 0.375 inches long. The field brush was completely disintegrated, with the spring contacting the slip ring. This alternator is only available from the manufacturer. There are no known third-party overhaul facilities.

Part Total Time: 645.0 hours