Amateur-built Exec 90 accident near Caldwell, Idaho, October 19, 2016
On October 19, 2016 at about 3:10 pm local time, a 1998 amateur-built Exec 90 (helicopter), registered N716JB, was substantially damaged in an accident during takeoff near Caldwell, Idaho (Caldwell Industrial airport). It was a personal flight under general aviation rules (Part 91). 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 pilot's failure to properly tighten the tension bolts during the installation of the alternator belt, which resulted in inadequate voltage to sustain ignition and the subsequent partial loss of engine power.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- October 19, 2016 · about 3:10 pm local time
- Place
- Caldwell, Idaho · Caldwell Industrial · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built Exec 90, built 1998
- Registration
- N716JB · registry record · serial Exec-3000
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
Shortly after takeoff for the personal flight, about 15 to 20 ft above ground level, the experimental amateur-built helicopter suddenly yawed right, followed by a partial loss of engine power. The private pilot then performed a partial nose-up, collective-down maneuver, but due to the low altitude and not being able to maintain sufficient rotor rpm, he chose to land in soft dirt off the side of the runway; the helicopter landed hard. The pilot had recently changed the alternator belt. A postaccident examination of the helicopter revealed that, during the maintenance, the pilot failed to properly tighten the tension bolts, which resulted in inadequate voltage to sustain ignition and the subsequent partial loss of engine power.
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
What happened, in order
- Loss of engine power (partial) during takeoff defining event
- Hard landing during landing (flare/touchdown)
The NTSB's findings
- cause Aircraft › Aircraft power plant › Ignition system › Ignition power supply › Incorrect service/maintenance
- cause Personnel issues › Task performance › Maintenance › Installation › Pilot
Pilot
- Certificate: private
- Ratings: single-engine land; rotorcraft: helicopter
- Flight time: 577 hours in all; 403 in this make and model; 50 in the last 90 days; 16 in the last 30 days; 422 as pilot in command
- Last flight review: September 29, 2015
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 223 hours
- Last inspection: continuous airworthiness programme, February 28, 2016; 223 hours since
- Maximum gross weight: 1,500 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotorway 55005 (piston); 322 hours total
The flight
- Departed from: EUL Caldwell ID at 3:00 pm
- Destination: EUL Caldwell ID
- Flight plan: none
- Runway 12, 5,500 ft by 100 ft
Weather at the time
- Light: daylight
- Wind: from 040° at 4 knots
- Visibility: 8 statute miles
- Sky: clear
- Temperature: 37°F (3°C), dew point 36°F (2°C)
- Altimeter: 30.02 inHg
- Observation at 2:56 pm from EUL
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.
Other NTSB records under N716JB the same tail number, which may have belonged to a different aircraft at the time
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.