# NTSB LAX88FA241: Helio HST-550A, N9991F, Perris, CA, June 30, 1988

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: June 30, 1988, 13:00 local (20:00 UTC)
- Place: Perris, CA
- Location: 33.7825° N, 117.2286° W: Placed by OpenAirDocs: center of Perris, CA, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=33.7825&lon=-117.2286&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed, report July 9, 1990
- Report: Approved by Office Director
- NTSB case key (mKey): 25841
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX88FA241
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/25841/pdf
- Page: https://openairdocs.org/ntsb/LAX88FA241

## Probable cause

FAILURE OF THE ELECTRICAL STABILIZER TRIM CONTROL THAT RESULTED IN AN UNCOMMANDED FULL NOSE DOWN ELEVATOR TRIM COMMAND.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Loss of control - in flight, descent - normal
  - flt control syst,stabilator trim - failure,total (cause)
  - elevator trim - uncontrolled (cause)
- In flight collision with terrain/water, descent - uncontrolled
  - object - vehicle (contributing factor)
  - object - building(nonresidential) (contributing factor)

## Analysis

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.

## Aircraft

- Registration: [N9991F](https://openairdocs.org/deregistered/N9991F-1988-08-26), registration cancelled 1988-08-26, S/N 004 (OpenAirDocs)
- Reported make and model: HELIO HST-550A
- Registry model: [Helio HST-550A](https://openairdocs.org/model/helio-hst-550a) (registry code 4301006) (OpenAirDocs)
- Category: Airplane
- Serial number: 004
- Airframe hours: 2100
- Engines: P&W PT-6A-27 680 horsepower turbo prop
- Damage: Destroyed
- Flight: Skydiving, Part 91
- Operator: Perris Valley Skydiving Inc.
- Registered owner: Perry, James D
- Airworthiness certificate: Standard, Utility; Standard, Normal
- Last inspection: 100 hour, June 30, 1988, 25 hours before
- Departed: L65, PERRIS, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 48; airline transport, commercial; airplane ratings: single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 4,500 total, 4,500 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: 300° at 8 knots
- Visibility: 3 statute miles
- Lowest ceiling: none
- Temperature: 91 °F, dew point 59 °F
- Altimeter: 29.00 inHg
- Observed at: RIV, 7 nm away

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19880630027299A](https://openairdocs.org/incident/19880630027299A), Jun 30, 1988: Helio HST550A, Perris, CA, Destroyed, 1 fatal. Pitch trim in full down position after dropping skydivers. No time to parachute.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.