Chafed, Corroded

The following information is derived from the FAA's Service Difficulty Reports and Aviation Maintenance Alerts.


Cessna 150B Corroded Wing Spars
Corrosion was found on the forward and aft wing spars under the fuel tank spacer blocks (p/n 0523524) in the fuel tank mounting bay. This problem was discovered when the fuel tanks were removed for repair. No visual corrosion indications were noted around the spacers before removal. These spacers were removed on a “hunch” underlying corrosion might exist. The condition was found in both wings.

Part Total Time: 7400.0 hours

Pilatus PC-12/47 Failed Brake Disk
Upon wheel removal during a scheduled inspection, one of the brake disk assemblies fell onto the floor in two separate pieces. Both left and right brake assemblies presented separated brake disks. Neither the operator nor the technicians noted abnormal sounds or conditions prior to disassembly.

Part Total Time: 1043.0 hours

Rotax 912S3 Chafed Coolant Hose
The lower engine coolant hose and exhaust SCAT hose are in constant contact due to installation design. Chafing caused wire from the SCAT hose to puncture the lower coolant hose. Subsequent loss of all coolant caused engine overheating. The only way to inspect is to remove the SCAT hose.

Part Total Time: 161.0 hours

Champion Spark Plug RHB32S Cracked Insulators
The turbocharged engine in a Cirrus SR22 ran rough during climb to 14,000 feet. The pilot could not set cruise fuel flow. After noting rising CHT and TIT, along with decreasing oil pressure, the pilot diverted for landing. Inspection revealed damage throughout the engine, including no differential pressure on cylinder number two and an oil filter full of metal. An annual inspection had been completed 30 flight hours earlier.

Part Total Time: 30.0 hours

Sky-tec Starter C24SF3 Shorted Commutator
After starting the Cirrus SR20’s TCM IO-360-ES engine, the right PFD went blank. Maintenance suspected a bad battery and installed a new one. When the negative wire was installed, a large spark was generated. The Battery No. 1 relay was stuck. After replacing the relay, the engine would not start. The old starter was replaced and disassembled. A dead short was discovered, caused by a section of the commutator coming loose. It had discharged the battery, causing the relay to stick closed.

Part Total Time: 850.0 hours


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