Amateur-built EXEC 90 accident near Chandler, Arizona, February 9, 1993
On February 9, 1993 at about 9:55 pm local time, a amateur-built EXEC 90 (helicopter), registered N89678, was substantially damaged in an accident near Chandler, Arizona. It was an other work-use 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 MANUFACTURER'S INADEQUATE QUALITY CONTROL WHICH RESULTED IN THE FATIGUE OF THE VALVE STEM. THE SOFT TERRAIN CONTRIBUTED TO THIS ACCIDENT.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- February 9, 1993 · about 9:55 pm local time
- Place
- Chandler, Arizona · 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
- Registration
- N89678 · no longer on the register · serial R.I. 5026
- Damage
- Substantial damage
- Flight
- Other work-use flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
THE HELICOPTER'S ENGINE FAILED WHILE ON THE CROSSWIND LEG. THE SURROUNDING TERRAIN WAS CONGESTED FORCING THE PILOT TO LAND IN AN AREA WHICH WAS DOWNWIND. THE HELICOPTER NOSED DOWN ON LANDING IN THE SOFT TERRAIN. EXAMINATION OF THE ENGINE DISCLOSED THAT AN INTAKE VALVE FAILED AND LODGED IN THE PISTON. METALLURGICAL EXAMINATION REVEALED THAT THE VALVE STEM FAILED IN FATIGUE. THE FATIGUE WAS PRECIPITATED BY THE MANUFACTURER'S IMPROPER QUALITY CONTROL WHICH FAILED TO ASSURE THAT THE VALVE WAS GROUND BEFORE IT WAS PLATED.
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: flight instructor, commercial pilot
- Ratings: single-engine land; instructor: helicopter; rotorcraft: helicopter
- Flight time: 1,059 hours in all; 611 in this make and model; 111 in the last 90 days; 55 in the last 30 days; 979 as pilot in command; 654 on instruments
- Medical certificate: Class 2 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 541 hours
- Last inspection: continuous airworthiness programme, January 11, 1993; 20 hours since
- Maximum gross weight: 1,425 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotorway 162 (piston); 0 hours total
- Operator: Cobb International, INC.
The flight
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 270° at 12 knots
- Visibility: 35 statute miles
- Sky: scat at 1,500 ft
- Temperature: 61°F (16°C), dew point 0°F (-18°C)
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.
Other NTSB records under N89678 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.