CESSNA 172S: A 100-hour inspection revealed four (of six) cracked bolt holes in the propeller spinner bulkhead (P/N 0552231-1). The mechanic suspects current propeller bolt torque values induce too much stress for the through-holes as bulkhead metal is formed into the chamfered area of the propeller bolt passages during torque. His suggested correction would be a part redesign and/or heavier material for bulkhead manufacture. (January's SDRS submissions include identical defects in four additional 172s. They will be added to the SDRS database, which then will reflect an approximate 37 records of this model 172 aircraft defect since 1995.) Part Total Time: 96.6 hours.

LEARJET 35A: The flight crew reported aircraft gear extension took longer than normal, but "down and locked" was achieved. Moments later all hydraulic pressure was gone. A safe landing was made using emergency brake pressure. Gear swings under maintenance scrutiny revealed a pinhole in the L/H spoiler-down line (P/N 26007003-375) located in the top center wing section. Corrosion is suspected as the probable cause. Part total time: 7993.7 hours.

SIKORSKY S76A: A pilot performing a postflight check noticed a large amount of oil on the ground. Further inspection by a technician revealed that a fastener (P/N 9550158060) on the L/H side of the oil cooler ducting panel (P/N 0401272790) had come loose and had worn a hole on the inboard side of the oil supply line (P/N 0401274100). The mechanic recommends a daily inspection of the above fastener(s) to ensure their security.

MITSUBISHI MU2B-40: A 400-hour special engine inspection found the aft bearing was loose in the starter/generator (Lucas P/N 23046-028). The aft bearing retainer screws had partially backed out (bearing support P/N 23046-110). The submitter states: "Bearing failure can cause catastrophic failure of the starter/generator." Four MS35265-43 screws with drilled heads hold the retainer to the frame. These four screws were not safety wired, and apparently, safety wire is not called for and is not described in the available component maintenance manuals for the starter/generator. The writer concluded that he tightened and safety-wired the screws, then returned the unit to service. Caution is recommended to operators using this starter/generator and operators should periodically remove the unit and cooling fan cover to verify bearing retainer security.