CHI98FA313 · Hiller FH-1100
Hiller FH-1100 · Accident: rotor failure/malfunction en route
From Grand Ledge, MI to ST. JOHNS, MI
Event
- NTSB case
- CHI98FA313
- Event typeAccident: someone killed or seriously injured, or the aircraft substantially damaged (NTSB definition). Incident: an occurrence that affected or could have affected safety, short of that. Glossary
- Accident
- InvestigationHow far the investigation had got when the record was published: preliminary, ongoing, final or completed. Unknown where the source does not say. Glossary
- Completed
- API-reported fatalities
- 1 · all aircraft and ground
- Ground fatalities
- 0
- OperationWhat kind of flying it was, grouped by the rules it flew under: airline (US Part 121), air taxi and commuter (Part 135), general aviation (Part 91 and similar), military or government. Glossary
- General aviation
- WeatherVisual meteorological conditions (VMC): good enough to fly by looking outside. Instrument conditions (IMC): cloud or low visibility, flying by instruments. Glossary
- Visual Meteorological Cond
Hiller FH-1100
- Aircraft type
- Hiller FH-1100
- Category
- Helicopter
- RegistrationThe aircraft's tail number, such as N12345 or G-ABCD. Registrations are reissued, so the same one years apart can be a different aircraft. Glossary
- N8171U
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Grand Ledge, MITo ST. JOHNS, MI
- Aircraft age
- Not recorded
- Flight rulesThe regulations the flight operated under: in the US, Part 91 (general aviation), Part 121 (airlines), Part 135 (air taxi and commuter) and others; for flights abroad, the NTSB's coarser commercial or non-commercial code. Glossary
- Part 91: General Aviation
- Phase of flightThe stage of the flight when things started to go wrong: standing, taxi, takeoff, initial climb, en route, maneuvering, approach or landing. Glossary
- En route · cruise
- First occurrenceThe single coded event the NTSB judges best describes what happened (records from 2008 on). Older records name the first occurrence in the sequence instead. Glossary
- Rotor failure/malfunction
- DamageDestroyed: beyond practical repair. Substantial: damage that affects the structure, performance or handling and normally needs major repair. Minor: less than that. Glossary
- Destroyed
Cause areas
- Company/operator management › Maintenance, inspection, inadequate
- Other maintenance personnel › Procedure inadequate
- Rotor system, tail rotor blade › Debonded
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
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.
Probable cause
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.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record CHI98FA313
- Event ID
- 20001211X10785
- Case number
- CHI98FA313
- Dataset
- historical-pre2008
- Source SHA-256
- 89e2df6d848e7ab3b42e7d7c7a03ff403303057a26ca04c95b3ea67201c3ce74
Source notes (4)
- Unreviewed is an editorial label, not an investigation status. API-sourced is not report-checked or human-reviewed. Explicit event totals are used without summing aircraft injury tables; onboard allocation is withheld. Unknown values remain unknown. The operation category is mapped from the NTSB-reported FAR part and has not been reviewed.
- Filled from the NTSB case API where the bulk record had no value: investigation status. Values present in the bulk record are kept.
- The date is the local date, which is the same as the UTC date the NTSB stores.
- API snapshot SHA-256: 450162ee702159e5d062bcf239de1b794f888d9a9406c03095cff657f0ad461d; retrieved 2026-09-20T22:27:56.270Z.