Amateur-built 162F accident near Phoenix, Arizona, May 31, 1997
On May 31, 1997 at about 2:05 pm local time, a amateur-built 162F (helicopter), registered N176BT, was destroyed in an accident near Phoenix, Arizona (Phoenix-Deer Valley Muni airport). It was a personal 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 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.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 31, 1997 · about 2:05 pm local time
- Place
- Phoenix, Arizona · Phoenix-Deer Valley Muni · map
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built 162F
- Registration
- N176BT · no longer on the register · serial 6144
- Damage
- Destroyed
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
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.
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: foreign licence, private
- Ratings: single-engine land; rotorcraft: helicopter
- Flight time: 250 hours in all
- Medical certificate: Class 3 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Last inspection: inspection type not recorded
- Maximum gross weight: 1,425 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotorway RI-162F (piston); 0 hours total
- Fire on the ground
The flight
- Departed from: DVT at 1:20 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 060° at 6 knots
- Visibility: 50 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 39°F (4°C)
- Altimeter: 29.00 inHg
- Observation at 1:10 pm from DVT
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.