LAX97LA197 · Rotorway 162F
Rotorway 162F · Accident: airframe, component or system failure en route
From Phoenix Deer Valley Airport (DVT) to an unrecorded destination
Event
- NTSB case
- LAX97LA197
- 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
Rotorway 162F
- Aircraft type
- Rotorway 162
- 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
- N176BT
- Operator
- Unknown
- Onboard fatalities
- Unknown
- Route
- From Phoenix Deer Valley Airport (DVT)To not recorded
- 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 · descent
- 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
- Airframe, component or system failure
- 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
- Owner/builder › Maintenance, installation, inadequate
- Owner/builder › Maintenance, lubrication, not performed
- Pilot in command › Rotor RPM, not maintained
- Rotor drive system, tail rotor drive shaft › Failure
- Rotor drive system, tail rotor drive shaft › Incorrect
- Rotor drive system, tail rotor drive shaft › Overtemperature
- Rotor drive system, tail rotor drive shaft › Overtorque
Approximate · Coordinates as recorded by the NTSB; no uncertainty radius is established.
NTSB narrative
While inbound to an airport, the pilot transmitted 'mayday' twice, but did not state the nature of the emergency. Witnesses saw the helicopter spin 4 to 5 revolutions, then it stopped spinning & fell to the ground. Reportedly, the rotors stopped turning before ground impact. Exam of the helicopter revealed the pivot bolts & brackets for the tail rotor drive assemblies had been overtorqued, & the pivot belts had no lubrication on the bolts or associated surfaces. The tail rotor drive belt was found frayed & shredded. Both idler pulleys & their associated mountings had not been constructed or installed correctly. A tail rotor belt advisory bulletin from Rotorway advised that temperature strips be installed on the 2 tail rotor idler pulleys & the drive pulley. It required an exam of the temperature strips before & after each flight, & it cautioned that if the 170-degree dot darkened, that was an indication that a belt may be slipping or some other problem existed; & if the 180-degree dot darkened, the belts had been damaged from heat & must be replaced. Temperature dots on this helicopter indicated the temperature had exceeded 200 degrees. The owner/builder was instructed to visually check the travel of the idler pulley swing arm, condition of the drive belts, condition of the pulleys & bearings, & temperature strips during preflight inspection. Visual inspection revealed no evidence that the inspection door had ever been opened, since the original paint seal had never been broken.
Probable cause
the owner/builder incorrectly installed the tail rotor drive pulley mounting scissors, overtorqued the pivot belts, did not perform the required maintenance lubrication of the pivot belts, and failed to perform adequate visual maintenance checks of these areas during the pre/postflight checks; the resultant overtemperature on the pulley idlers; eventual catastrophic failure of the drive belts; and the pilot's failure to maintain rotor rpm during autorotation, which resulted in loss of aircraft control and subsequent collision with the terrain.
Verbatim NTSB analysis and probable cause from the NTSB dataset
Sources
NTSB record LAX97LA197
- Event ID
- 20001208X07963
- Case number
- LAX97LA197
- 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: 46797b1cf3de524b0528d84b43fed8dca0c7ff54d52fd10b96b6ea17d8309255; retrieved 2026-09-20T22:56:58.506Z.