Grumman G-164B accident near Helena, Montana, June 15, 1995
On June 15, 1995 at about 4:30 pm local time, a Grumman G-164B, registered N6669Q, was destroyed in an accident near Helena, Montana. It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
THE LOSS OF ENGINE POWER FOR UNDETERMINED REASONS.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 15, 1995 · about 4:30 pm local time
- Place
- Helena, Montana · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Grumman G-164B · all G-164Bs on the register
- Registration
- N6669Q · no longer on the register · serial 191B
- Damage
- Destroyed
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
WHILE MANEUVERING IN CLOSE PROXIMITY TO THE GROUND, THE ENGINE BACKFIRED TWO OR THREE TIMES AND SUDDENLY LOST POWER. THE PILOT ATTEMPTED TO LEVEL THE WINGS AND EXECUTE A FORCED LANDING, BUT THE AIRPLANE IMPACTED TERRAIN IN A BANK. EXAMINATION OF THE ENGINE REVEALED THAT THE CRANKSHAFT WAS BINDING DURING ROTATION, THE NO. 5 CYLINDER HEAD WAS CRACKED, AND THE CRANKSHAFT WAS EXPOSED TO HEAT DISTRESS. NO EVIDENCE WAS FOUND TO INDICATE THAT THESE DEFICIENCIES OCCURRED AFTER THE ACCIDENT. POSTIMPACT AND THERMAL DAMAGE TO THE ENGINE PRECLUDED A COMPLETE FUNCTIONAL TEST AND EXAMINATION OF THE ENGINE.
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: single-engine land; instrument: airplane
- Flight time: 5,889 hours in all; 1,800 in this make and model; 100 in the last 90 days; 5,889 as pilot in command
- Medical certificate: Class 2 (valid medical--w/ waivers/lim.)
- Seat: frt
The aircraft
- Airframe total time: 3,200 hours
- Last inspection: annual inspection, March 30, 1995
- Maximum gross weight: 6,075 lb
- Seats: 1
- Landing gear: fixed
- Engine: P&W 1340-AN1 (piston); 0 hours total
- Fire on the ground
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 060° at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 68°F (20°C), dew point 54°F (12°C)
- Altimeter: 29.00 inHg
- Observation at 3:54 pm from HLN, 18 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.