NTSB Identification: SEA00LA188.
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Accident occurred Sunday, September 24, 2000 in BURLINGTON, WA
Probable Cause Approval Date: 07/17/2001
Aircraft: Hughes 269B, registration: N9355F
Injuries: 3 Minor.
NTSB investigators may have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot aborted his landing in the Hughes 269B helicopter after encountering dust and reduced visibility at the landing site. During the climbout, and at 50-60 mph and approximately 140 feet above ground, the engine rapidly lost power. The pilot executed an autorotation landing from an airspeed/altitude condition slightly outside the limitations of the height-velocity diagram and landed hard. Post crash examination revealed that the #1 cylinder fuel injector line had separated approximately one inch outboard of the injector unit. Metallurgical examination revealed the separation as fatigue. The engine log showed this to be the second #1 cylinder fuel injector line separation in recent history. Further examination revealed that 3 of the hold down bolts for the #3 cylinder had separated and metallurgical examination revealed the separations as fatigue. The flange for the #3 cylinder was observed to be painted with primer paint measuring from about 0.0014 inch to 0.0028 inch in thickness. Both cylinder hold down plates were examined and showed fretting and rubbing damage. According to Textron Lycoming Service Bulletin 271A, the primer paint thickness on the flange should not exceed 0.0005 inch. According to the engine log the engine underwent a major overhaul on July 8, 1994, during which the '...engine was painted assembled and delivered to Cascade Airframe Repair....' The #3 cylinder was subsequently removed and honed on an unspecified date. The date when the #3 cylinder flange was painted was not determined.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Mintenance personnel not following the mandatory service bulletin procedure of not exceeding 0.0005 inch paint thickness on the cylinder flange. Factors were the fatigue separation of multiple cylinder hold down bolts resulting in looseness of the cylinder; and the subsequent vibration and fatigue separation of the fuel injector line. An additional factor was the pilot's operation of the rotorcraft outside the height/velocity parameters for a successful autorotation. Full narrative available
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