April 2012 FAA Maintenance Alerts

Cessna: 402C; Failed Nose Gear Microswitch; ATA 3260

"The nose gear collapsed on landing," says this electrical technician. "The nose gear actuator was removed and tested in a controlled environment. When the actuator was cold soaked, the microswitch (P/N 1CH16) failed to activate properly, giving a false indication the gear was down and locked. Due to gear failure, both aircraft propellers struck the ground and caused sudden stoppage to the engines. The aircraft also suffered structural damage to the nose section."

Part Total Time: 352.0 hours

Hawker: 800XP; Failed Elevator Trim Rod-ends; ATA 2731

A submitter writes, "When conducting a maintenance preflight inspection, the technician noticed rust stains coming from the aft rod-ends (P/N CN635MESP56) of the elevator trim tab rod on both left and right elevator trim tabs. Further inspection revealed the grease seals on one end of both the left and right trim tab rod-ends had come off, and the ball bearings were mostly missing. Fortunately, the other rod-end on each of the trim tabs was still intact. However, rust stains were also noticed coming through these grease seals. In the process of replacing the rod-ends, it was noticed that TKS deicing fluid had penetrated into the hollow inner portion of the trim tab control rod, (but) no evidence of corrosion existed. Recommendation: Conduct a close-up visual inspection of the elevator trim tab rod-ends for rust staining and grease seal separation on an annual basis. Any time rust staining is observed coming out of the rod-ends, replace them. At each 48-month inspection, remove the rod-ends and visually inspect the control rods for corrosion."

Part Total Time: 4,520.0 hours

Superior Cylinder: SL36006WA1E; Cracked; ATA 8530

"During an Annual compression test this cylinder was found to have no compression," says a mechanic. "Upon further investigation, air was found leaking from the back of the cylinder assembly at the point where the fins step up to the next size. With an inspection mirror held between the baffling and the back of the cylinder, a crack could be seen. (I) removed the cylinder from the engine and found this crack started at the top spark plug hole, continuing towards the back of the cylinder, and down and through the exhaust valve seat to the rear exhaust mounting stud. This Superior Air Parts cylinder was installed new in February 2005. AD 2007-04-19R1 deals with cracks at the barrel/head in cylinder assemblies manufactured between April and November of 2005. Maybe this AD should be expanded to include these assemblies. Other cylinder markings include an etching number E36-14165, and a casting number SLC-36005."

Part Total Time: 1,533.0 hours

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