Amateur-built EXEC accident near Caldwell, Idaho, December 17, 2017
On December 17, 2017 at about 8:00 pm local time, a 1998 amateur-built EXEC (helicopter), registered N716JB, was substantially damaged in an accident during maneuvering (hover) 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
Failure of the oil pressure gauge line, which resulted in oil exhaustion and a total 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
- December 17, 2017 · about 8:00 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
The private pilot was performing hover-taxi maneuvers in the experimental amateur-built helicopter when the engine lost all power, which resulted in a forced landing in a field during which the airplane landed hard. Postaccident examination revealed that the engine had seized due to oil exhaustion after the oil pressure gauge line had failed, causing most of the engine oil to be expelled overboard with an insufficient quantity of oil in the sump for engine operation. The pilot, who was also the helicopter builder, had installed the oil pressure gauge line, which was made of automotive-grade nylon tubing, about 1 year before the accident. Because the helicopter had an experimental airworthiness certificate and was considered to be an amateur-built aircraft, the pilot could use non-aviation grade components. The pilot discarded the oil line before it could be examined, so its failure mode could not be determined.
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
- Powerplant sys/comp malf/fail during maneuvering (hover) defining event
- Loss of engine power (total) during maneuvering (hover)
- Off-field or emergency landing during emergency descent
- Hard landing during landing
The NTSB's findings
- cause Aircraft › Aircraft power plant › Eng oil sys (airframe furnish) › Engine oil indicating system › Failure
- cause Aircraft › Fluids/misc hardware › Fluids › Oil › Fluid level
Pilot
- Certificate: private
- Ratings: single-engine land; instrument: airplane; instrument: helicopter; rotorcraft: helicopter
- Flight time: 691 hours in all; 317 in this make and model; 33.4 in the last 90 days; 11.1 in the last 30 days
- Last flight review: October 19, 2017
- Medical certificate: Class 3 (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 317 hours
- Last inspection: condition inspection, August 5, 2017; 21 hours since
- Maximum gross weight: 1,350 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotorway RW-152 (piston); 315 hours total
The flight
- Departed from: EUL Caldwell ID at 7:30 pm
- Destination: EUL Caldwell ID
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 090° at 3 knots
- Visibility: 10 statute miles
- Sky: overcast at 6,000 ft
- Temperature: 36°F (2°C), dew point 23°F (-5°C)
- Altimeter: 30.28 inHg
- Observation at 7:56 pm from KEUL
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
2 documents, released by the NTSB on October 22, 2018. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Pilot Interview Summary | PDF, 1 page | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
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.