Hiller FH-1100 accident near Dewitt, Michigan, August 14, 1998
On August 14, 1998 at about 8:20 pm local time, a Hiller FH-1100 (helicopter), registered N8171U, was destroyed in an accident near Dewitt, Michigan. It was a business flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
The rotor failure/malfunction due to debonding of the tail rotor blade. Also causal was the inadequate maintenance inspection of the aircraft by the company and the improper maintenance procedure by other maintenance personnel.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 14, 1998 · about 8:20 pm local time
- Place
- Dewitt, Michigan · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Hiller FH-1100
- Registration
- N8171U · no longer on the register · serial 254
- Damage
- Destroyed
- Flight
- Business flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
A Hiller FH-1100 was destroyed on impact with terrain following the separation of a tail rotor blade in cruise flight. The tail rotor blade 'B' was separated 1/4 span from its root and was discovered 700 feet south of the main wreckage. Blade 'A' was found 850 feet south of the main wreckage. The tail rotor blades were overhauled and later removed for blade delamination on July 14, 1986. The inside surfaces of the blade 'A's' skin showed longitudinal streak patterns of debris. The skin trailing edge closure bond contained an adhesive that was bright purple in color. During 1967-1982 tail rotor blades were bonded with FM1000; a cream or off white colored adhesive. Since 1982, FM1000 bonded the skin and doubler and FM73, which is orange brown in color, between the root fitting and doubler. The rivet holes in the skin were worn on the skin surfaces under the upset heads of the rivets. No wear was visible under the manufactured heads. The rivet holes were not round and appeared to have two overlapping diameters consistent with double drilling. The Hiller FH1100 Overhaul Manual Tail Rotor Assembly, Repair - Tail Rotor Blade Assembly, states, '...Replacement of skin, doubler or rib ... is not permitted.' The Hiller FH1100 Inspection Guide described the inspection of the tail rotor blades during preflight, 100-hour inspection and 300-hour inspection.
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: multi-engine land; single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 4,326 hours in all; 86 in this make and model; 4,130 as pilot in command
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 3,821 hours
- Last inspection: annual inspection, February 1, 1997; 135 hours since
- Maximum gross weight: 3,000 lb
- Seats: 5
- Landing gear: fixed
- Engine: Allison 25-C18B (turboshaft); 0 hours total
The flight
- Departed from: Grand Ledge MI at 8:07 pm
- Destination: St. Johns MI
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 210° at 8 knots
- Visibility: 10 statute miles
- Sky: scat at 7,500 ft
- Temperature: 81°F (27°C), dew point 57°F (14°C)
- Altimeter: 29.00 inHg
- Observation at 3:55 pm from LAN, 17 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.