Date:	Saturday 13 August 1994
Time:	13:31
Type:	Lockheed C-130A Hercules
Owner/operator:	Hemet Valley Flying Service
Registration:	N135FF
MSN:	3148
Year of manufacture:	1957
Total airframe hrs:	20300 hours
Engine model:	Allison T56-A-9D
Fatalities:	Fatalities: 3 / Occupants: 3
Aircraft damage:	Destroyed, written off
Category:	Accident
Location:	ca 11 km S of Pearblossom, CA -   United States of America
Phase:	Manoeuvring (airshow, firefighting, ag.ops.)
Nature:	Fire fighting
Departure airport:	Hemet-Ryan Field, CA (HMT/KHMT)
Destination airport:	Hemet-Ryan Field, CA (HMT/KHMT)
Investigating agency:	NTSB
Confidence Rating:	Accident investigation report completed and information captured

Narrative:
The Hercules was on its way to a forest fire in the Tehachipi Mountains when it lost control and crashed on the north face of Pleasant View Ridge in the vicinity of Pechner Canyon at about the 6,500 foot level. The right wing (including no. 3 and no. 4 engine) had failed in-flight following a fuel tank explosion. The aircraft in question had been in storage for 2 years and had a history of fuel leaks in the dry bay area. The source of which usually being flattened or pinched O-rings which are on-condition replacement items. Inspection for leaks in this area are required before flight. The dry bay area of the right wing contains high pressure fuel lines, unshielded and exposed electrical wiring and is in close proximity to the no. 3 engine. This initially led to the following probable cause: "the ignition of fuel leaking from the pressurized fuel system lines in or adjacent to the No. 3 dry bay, most likely due to electrical arcing and/or hot surfaces in the No. 3 engine."
Following two air tanker accidents in 2002 the NTSB reviewed the accident information, including the examination of wreckage that was not recovered in the initial investigation. This revealed previously undiscovered evidence of fatigue fracturing in right-side, center-wing fragments that supported revising the probable cause.

PROBABLE CAUSE: "The inflight failure of the right wing due to fatigue cracking in the underside right wing skin and overlying doubler. A factor contributing to the accident was inadequate maintenance procedures to detect fatigue cracking."

ICAO Adrep Summary 6/95 (#37)
NTSB id. LAX94FA323
Scramble 187

photo (c) via Werner Fischdick; Hemet-Ryan Field, CA (HMT); February 1992

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