Aerospatiale SA-315B accident near Tok, Alaska, August 7, 1990
On August 7, 1990 at about 8:30 pm local time, a Aerospatiale SA-315B (helicopter), registered N58000, was substantially damaged in an accident near Tok, Alaska. It was an other work-use flight under external-load helicopter rules (Part 133). 1 person was seriously injured. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
IMPROPER INSTALLATION OF THE FUEL FILTER ELEMENT IN THE AIRCRAFT BY COMPANY/MAINTENANCE PERSONNEL, AND SUBSEQUENT CONTAMINATION OF THE FUEL SYSTEM BY UNFILTERED FUEL. FACTORS RELATED TO THE ACCIDENT WERE: INADEQUATE DESIGN OF THE FUEL FILTER ASSEMBLY, WHICH ALLOWED THE IMPROPER INSTALLATION OF THE FILTER ELEMENT, THE MECHANICS LACK OF FAMILIARITY WITH THE AIRCRAFT, AND FAILURE OF GROUND PERSONNEL TO INSURE THAT FUEL FROM THE FUEL TANKER WAS FREE OF CONTAMINATION.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 7, 1990 · about 8:30 pm local time
- Place
- Tok, Alaska · map
- Type
- Accident
- Injuries
- 1 person was seriously injured.
- Weather
- visual conditions (good weather)
- Aircraft
- Aerospatiale SA-315B · all SA-315Bs on the register
- Registration
- N58000 · registry record · serial 2639
- Damage
- Substantial damage
- Flight
- Other work-use flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
THE HELICOPTER WAS BEING USED IN AN EXTERNAL LOAD OPN TO CARRY CARGO WITH A 100 FT CABLE. WHILE HOVERING OUT OF GROUND EFFECT, THE ENG LOST PWR. A SUBSEQUENT HOVERING AUTOROTATION RESULTED IN A HARD LANDING. AN EXAM REVEALED THE LOSS OF POWER WAS DUE TO FUEL CONTAMINATION ALTHOUGH AN AIRFRAME FUEL FILTER WAS INSTALLED IN THE MAIN FUEL SUPPLY LINE. AN EXAM REVEALED THE FILTER ELEMENT HAD BEEN INSTALLED BACKWARD IN THE FILTER CANISTER. THIS ALLOWED CONTAMINATED FUEL TO BYPASS THE FILTER ELEMENT & ENTER THE ENG FUEL CTL UNIT. THE REVERSE INSTLN ALSO RESULTED IN AN INOP 'FUEL FILTER CLOGGED' WARNING LGT & PREVENTED THE PRESSURE DIFFERENTIAL BUTTON ON THE FILTER HOUSING FM EXTDG. THE FILTER HAD BEEN INSPECTED & REINSTLD DRG A 100 HR INSPN, 17 FLT HRS BFR THE ACDNT. THIS WORK WAS DONE BY A PLT UNDER SUPERVISION OF A MECHANIC. THE MECHANIC HAD NO PREV EXPERIENCE WITH THIS MAKE & MODEL OF HELICOPTER. 'TOP' & 'BOTTOM' WERE STENCILED ON THE FILTER ELEMENT IN FRENCH. CONTAMINATED FUEL WAS ALSO FND IN THE FUEL TRUCK.
The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.
The factual record from the NTSB's investigation tables, in plain English
Pilot
- Certificate: commercial pilot
- Ratings: single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 13,000 hours in all; 5,000 in this make and model; 265 in the last 90 days; 98 in the last 30 days; 13,000 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: rgt
The aircraft
- Airframe total time: 3,607 hours
- Last inspection: 100-hour inspection, August 4, 1990; 17 hours since
- Maximum gross weight: 5,070 lb
- Seats: 5
- Landing gear: fixed
- Engine: Turbomeca ARTOUSTE IIIB (turboshaft); 0 hours total
The flight
- Departed from: TKJ Tok AK at 2:52 pm
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 220° at 10 knots, gusting 12
- Visibility: 50 statute miles
- Sky: broken clouds at 5,000 ft; not recorded
- Temperature: 63°F (17°C), dew point 0°F (-18°C)
- Altimeter: 29.00 inHg
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.