ANC95LA141

NTSB accident investigation · Short Brothers SC.7 · Nikolai, AK · August 11, 1995

Accident · No injuriesLimited investigationFinal report
Date
August 11, 1995, 10:30 local (18:30 UTC)
Place
Nikolai, AK
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N504FSShort Brothers SC.7
Weather
Visual (VMC) · Day
Status
Completed · report March 6, 1996
Report
Approved by Office Director
NTSB office
Alaska Regional Office
FAA report
19950811028649A
Case key
2719

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

Ignition of hazardous cargo (aviation fuel) by an exposed electrical wire, after leaking from a container of fuel that was being transported on the flight. Factors relating to the accident were: inadequate inspection of the airplane by company maintenance personnel, and failure of company personnel to identify the leaking fuel container.

Sequence of events

NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.

Hazardous materials leak/spillCruise
Cargo/baggage - leakFactor
Security of cargo - not verifiedGround personnelFactor
FireCruise
Electrical system,electric wiring - arcingCause
Maintenance,inspection - inadequateCompany maintenance personnelFactor
Fuselage - fireCause

Analysis

The pilot was delivering a load of cargo that included barrels of 100LL octane aviation fuel to a remote airstrip. The pilot reported fire and smoke in the cargo compartment. He began an immediate descent and landed at the destination airstrip. After landing, the pilot noticed that fuel was leaking from one of the barrels. The fire was located between the cargo area flooring and the bottom belly of the airplane. There was fire and heat damage to the cargo bay and melting of the airframe assembly, incorporating the rear spar and several airframe stations. An area of sooting and a charred section of electrical wiring was found below the flooring, adjacent to the mounting position of a lower fuselage beacon that had been removed sometime in the past. The circuit breaker protecting the electrical loads for the airplane's rotating beacons was found popped. Application of electrical power to the rotating beacon circuit resulted in proper functioning of the upper fuselage beacon and the presence of electrical power to the charred wiring.

Factual narrative

On August 11, 1995, about 1030 Alaska daylight time, a Short SC- 7, N504FS, experienced an in-flight fire about 20 miles from its planned destination at a private airstrip near Nikolai, Alaska. The airplane was being operated as a visual flight rules (VFR) cargo flight under Title 14 CFR Part 135 when the accident occurred. The airplane, registered to and operated by F.S. Air Service Inc., Anchorage, Alaska, sustained substantial damage. The certificated airline transport pilot, the sole occupant, was not injured. Visual meteorological conditions prevailed. Company flight following procedures were in effect. The flight originated from the Anchorage International Airport at 0927.

The operator reported that the cargo included barrels of 100LL octane aviation fuel. The pilot reported fire and smoke in the cargo compartment. He began an immediate descent and landed at the destination airstrip, located in a remote area. After landing, the pilot noticed that fuel was leaking from one of the barrels and from the belly of the airplane. The fire was extinguished by the pilot and ground personnel. The fire was located between the cargo area flooring and the bottom belly skin of the airplane.

Examination of the airplane on August 17, 1995, revealed fire damage to the flooring and heat damage to the overhead areas of the cargo bay. In addition, the airframe assembly incorporating the rear spar, the airframe formers between the rear and front spar, and airframe stations 211, 226, and 244, received fire damage and melting.

An area of sooting and a charred section of electrical wiring was found below the flooring near the aft end of the cargo bay. It was adjacent to the mounting position of a lower fuselage beacon that had been removed sometime in the past. The wire was connected to a 5 amp circuit breaker in the cockpit that was found popped. The breaker protected the electrical loads for the airplane's rotating beacons. Application of electrical power to the rotating beacon circuit resulted in proper functioning of the upper fuselage beacon, and the presence of electrical power to the charred section of lower fuselage wiring.

Aircraft

Registration
N504FS
Reported as
Short Brothers SC.7
Category
Airplane
Serial number
SH-1953
Airframe hours
5,965
Engine
Garrett TPE-331, 715 horsepower, turbo prop
Damage
Substantial damage
Fire
In-Flight
Flight
Part 135
Registered owner
F.S. Air Service Inc.
Airworthiness certificate
Standard, Normal
Last inspection
AAIP · August 7, 1995 · 5 hours before
Departed
ANC · Anchorage, AK
Flight plan
Company VFR

Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.

Flight crew

As NTSB recorded them. NTSB leaves out names.

Role
Pilot
Age
39
Certificates
Airline transport, Commercial
Airplane ratings
Multi-engine land, Single-engine land
Instrument ratings
Airplane
Medical
Class 1, Valid Medical--w/ waivers/lim
Seat
Left
Flight hours
6,100 total

Weather

Conditions
Visual (VMC) · Day
Wind
90° at 10 knots
Visibility
15 statute miles
Lowest ceiling
None
Temperature
61 °F

FAA reports on this event · 1

The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.