Southern Aero UH-1B accident near Skykomish, Washington, August 27, 1997
On August 27, 1997 at about 4:15 pm local time, a Southern Aero UH-1B (helicopter), registered N896W, was substantially damaged in an accident near Skykomish, Washington. It was an other work-use flight under external-load helicopter rules (Part 133). 1 person was killed. The weather was conditions the NTSB did not record.
The NTSB's probable cause their words, unchanged
A fatigue fracture in the main rotor mast, which resulted in an in flight separation of the main rotor from the helicopter. Contributing to the accident was insufficient Federal Aviation Administration airworthiness standards and requirements for the aircraft.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 27, 1997 · about 4:15 pm local time
- Place
- Skykomish, Washington · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- conditions the NTSB did not record
- Aircraft
- Southern Aero UH-1B
- Registration
- N896W · no longer on the register · serial 62-4576
- Damage
- Substantial damage
- Flight
- Other work-use flight · external-load helicopter rules (Part 133)
The NTSB's narrative final · quoted from the NTSB record
While performing external load logging operations, the helicopter's main rotor separated from the helicopter and the helicopter crashed. Metallurgical examination of the main rotor mast revealed a fatigue fracture in the upper spirolox groove in the damper support splines. Based on the mast's historical service record, the fractured mast, a Bell part number 204-011-450-001 mast assembly with a part number '204-040-466-9' mast tube (not a valid part number according to Bell), had 4,006.7 hours at the time of the mast separation. An FAA airworthiness directive (AD), AD 97-14-12, applicable to Bell 204B, 205A, 205A-1, 205B, and 212 civil helicopters but not to surplus military UH-1 helicopters, limited the life of part number 204-011-450-001 masts to 6,000 flight hours or a retirement index number (RIN) of 300,000 (the fractured mast had a RIN of 200,335, computed according to the method specified by that AD.) The most recent main rotor mast AD directly applicable to the accident helicopter, AD 89-17-03, limited mast life to 15,000 hours and contained no requirement to establish or track RIN. The 'thin-walled' Bell part number 204-040-366-9 mast tubes installed in part number 204-011-450-001 masts were ordered removed from U.S. Army UH-1 helicopters by a 1984 U.S. Army emergency safety-of-flight message.
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: airline transport pilot
- Ratings: single-engine land; instrument: airplane; rotorcraft: glider; rotorcraft: helicopter
- Flight time: 9,700 hours in all; 2,700 in this make and model; 123 in the last 90 days; 40 in the last 30 days; 9,600 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 9,177 hours
- Last inspection: 100-hour inspection, August 10, 1997; 23 hours since
- Maximum gross weight: 8,500 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming T53-L13B (turboshaft); 0 hours total
The flight
- Departed from: WA60 at 3:20 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 130° at 10 knots
- Visibility: 50 statute miles
- Sky: broken clouds at 4,300 ft; not recorded
- Temperature: 59°F (15°C), dew point 54°F (12°C)
- Altimeter: 30.00 inHg
- Observation at 3:50 pm from PAE, 39 miles away
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.