Notes: Accident Report:
Status: Final
Date: 13 AUG 1994
Time: 13:31 PDT
Type: Lockheed C-130A Hercules
Operator: Hemet Valley Flying Service
Registration: N135FF
C/n / msn: 3148
First flight: 1957
Total airframe hrs: 20300
Engines: 4 Allison T56-A-9D
Crew: Fatalities: 3 / Occupants: 3
Passengers: Fatalities: 0 / Occupants: 0
Total: Fatalities: 3 / Occupants: 3
Airplane damage: Destroyed
Airplane fate: Written off (damaged beyond repair)
Location: near Pearblossom, CA (United States of America)
Phase: Maneuvering (MNV)
Nature: Fire fighting
Departure airport: Hemet-Ryan Field, CA (HMT), United States of America
Destination airport: Hemet-Ryan Field, CA (HMT), United States of America
Descriptive:
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."