ASN Wikibase Occurrence # 43428
Last updated: 11 December 2013
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Narrative:The airplane was seen flying erratically, in a rapid descent, with smoke coming from the engine compartment and flames coming from the airplane's right side. Subsequently, the airplane crashed/landed and burned. An investigation revealed that the #1 cylinder had separated from the engine. Examination of the #1 cylinder revealed the upper crankcase thru-bolt at the 10 o'clock position had failed in fatigue below the cylinder deck surface. The lower thru-bolt at the cylinder pad's 8 o'clock position was intact; however, the nut was missing and the threads were battered and polished. The cylinder had 6 deck studs in addition to the thru-bolts. The studs at the 11 and 1 o'clock positions were missing; the studs at the 5 and 7 o'clock positions failed in fatigue; and the studs at the 2 and 4 o'clock positions were fractured with the fractured ends battered. Also, a silicon sealant (RTV) had been used on the thru-bolt threads, though not recommended by the manufacturer. The remaining thru-bolts were examined for tightness using a torque wrench; all were found undertorqued. During a top overhaul of the engine, about 85 flight hours before the accident, all of the cylinders had been removed and reinstalled. CAUSE: Improper top overhaul by maintenance personnel, and improperly torqued crackcase thru-bolts and cylinder deck studs at the number one cylinder, which led to fatigue failure of four of the bolts, failure and/or separation of the number one cylinder, and a subsequent fire.
Beechcraft G35 Bonanza
|C/n / msn:|| D-4643|
|Fatalities:||Fatalities: 1 / Occupants: 1|
|Airplane damage:|| Written off (damaged beyond repair)|
|Location:||West Palm Beach, FL -
United States of America
|Phase:|| En route|
|Departure airport:||Pahokee, FL (PHK)|
|Destination airport:||Wellington, FL|
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