Helio HST-550A accident near Perris, California, June 30, 1988
On June 30, 1988 at about 8:00 pm local time, a Helio HST-550A, registered N9991F, was destroyed in an accident near Perris, California. It was a skydiving flight under general aviation rules (Part 91). 1 person was killed. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
FAILURE OF THE ELECTRICAL STABILIZER TRIM CONTROL THAT RESULTED IN AN UNCOMMANDED FULL NOSE DOWN ELEVATOR TRIM COMMAND.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- June 30, 1988 · about 8:00 pm local time
- Place
- Perris, California
- Type
- Accident
- Injuries
- 1 person was killed.
- Weather
- visual conditions (good weather)
- Aircraft
- Helio HST-550A
- Registration
- N9991F · no longer on the register · serial 004
- Damage
- Destroyed
- Flight
- Skydiving flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
AFTER DROPPING SKYDIVERS THE PILOT ENTERED A DESCENT TO RETURN TO THE AIRPORT FOR ANOTHER LOAD OF JUMPERS. HE WAS RECEIVING RADAR ADVISORIES DURING THE DROP FROM A TRACON CONTROLLER. AS THE AIRCRAFT DESCENDED BELOW 4,000 FEET MSL THE CONTROLLER TERMINATED THE RADAR ADVISORY SERVICE. IMMEDIATELY AFTER THE CONTROLLER DISCONTINUED THE SERVICE HE ASKED THE PILOT TO CHECK FOR A STUCK MICROPHONE SWITCH. THE AIRCRAFT CONTINUED ITS DESCENT AND COLLIDED WITH A CAMPING TRAILER AND BUILDING UNDER CONSTRUCTION IN AN EXTREME NOSE LOW ATTITUDE. THE ELEVATOR TRIM WAS FOUND IN THE FULL NOSE DOWN POSITION. NO OTHER MALFUNCTIONS WERE FOUND.
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; single-engine sea; instrument: airplane
- Flight time: 4,500 hours in all; 4,500 as pilot in command
- Medical certificate: Class 1 (valid medical--w/ waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 2,100 hours
- Last inspection: 100-hour inspection, June 30, 1988; 25 hours since
- Maximum gross weight: 5,800 lb
- Seats: 10
- Landing gear: fixed
- Engine: P&W PT-6A-27 (turboprop); 0 hours total
- Operator: Perris Valley Skydiving INC.
The flight
- Departed from: L65 Perris CA at 7:30 pm
- Flight plan: none
- Runway 0
Weather at the time
- Light: daylight
- Wind: from 300° at 8 knots
- Visibility: 3 statute miles
- Sky: scat at 4,000 ft
- Temperature: 91°F (33°C), dew point 59°F (15°C)
- Altimeter: 29.00 inHg
- Observation at 7:55 pm from RIV, 7 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.