Bell UH-1B accident near Vero Beach, Florida, March 12, 1991
On March 12, 1991 at about 2:00 pm local time, a Bell UH-1B (helicopter), registered N9687R, was substantially damaged in an accident near Vero Beach, Florida (Unknown airport). It was an aerial application (crop spraying) flight under agricultural flying rules (Part 137). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
IMPROPER MAINTENANCE ADJUSTMENT BY COMPANY MAINTENANCE PERSONNEL RESULTING IN OVERTORQUE OF A TAILBOOM ATTACH BOLT WHICH ALLOWED THE TAILBOOM TO SHIFT. THIS DISENGAGED THE TAIL ROTOR DRIVE SHAFT AT A COUPLING RESULTING IN THE LOSS OF TAIL ROTOR DRIVE.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- March 12, 1991 · about 2:00 pm local time
- Place
- Vero Beach, Florida · Unknown · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Bell UH-1B · all UH-1Bs on the register
- Registration
- N9687R · no longer on the register · serial 62-12529
- Damage
- Substantial damage
- Flight
- Aerial application (crop spraying) flight · agricultural flying rules (Part 137)
The NTSB's narrative final · quoted from the NTSB record
SHORTLY AFTER TAKEOFF AT 40 FT AGL, THE PLT STATED THAT HE OBSERVED THE HIGH/LOW ROTOR/ENG WARNING LIGHT WAS ILLUMINATED & THE HELICOPTER ENTERED AN UNCOMMANDED RT YAW. HE ENTERED AN AUTOROTATION & WHILE DESCENDING, THE MAIN ROTOR BLADES CONTACTED TREES. HE PULLED COLLECTIVE PITCH BEFORE IMPACT WITH TERRAIN. EXAM OF THE HELICOPTER REVEALED THAT THE UPPER RT TAILBOOM ATTACH BOLT WAS STRIPPED WHICH ALLOWED THE TAILBOOM TO SHIFT RESULTING IN THE SEPARATION OF THE NOS. 1 & 2 TAIL ROTOR DRIVE SHAFT SECTIONS AT THE COUPLING. EXAM OF THE STRIPPED BOLT BY A QUALIFIED INDIVIDUAL REVEALED THAT IT FAILED DUE TO BEING OVERTORQUED. THE COMPANY MECHANIC STATED THAT THE TAILBOOM ATTACH BOLTS ARE CHECKED FOR PROPER TORQUE EVERY 100 HRS & WAS LAST ACCOMPLISHED ABOUT 55 HRS EARLIER.
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: airline transport pilot, commercial pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane; rotorcraft: helicopter
- Flight time: 5,120 hours in all; 1,420 in this make and model; 60 in the last 90 days; 60 in the last 30 days; 4,650 as pilot in command; 250 on instruments
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: unk
The aircraft
- Airframe total time: 7,047 hours
- Last inspection: 100-hour inspection, August 28, 1990; 55 hours since
- Maximum gross weight: 8,300 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming T53L11D (turboshaft); 0 hours total
- Operator: Colony Services, INC.
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: scat at 30,000 ft
- Temperature: 61°F (16°C), dew point 46°F (8°C)
- Altimeter: 30.00 inHg
- Observation at 1:53 pm from VRB, 5 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.