- Date
- August 24, 1991, 11:25 local (18:25 UTC)
- Place
- Santa Margarita, CA
- Injuries
- 1 serious, 1 minor
- Damage
- Destroyed
- Phase of flight
- Maneuvering
- Aircraft
- UNREGBeierle Thunder Gull J
- Weather
- Visual (VMC) · Day
- Status
- Completed
- Report
- Approved by Office Director
- Case key
- 27343
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
Probable cause
The failure of the wing spar when the design limits of the airplane was exceeded by the pilot. Contributing to the accident was an inadequate airframe design and an abrupt movement of the flight controls by the pilot.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
The certificated private pilot and a passenger were conducting a flight test of an unregistered, homebuilt airplane. The airplane was being marketed as an ultralight vehicle with an exception of the ultralight regulations granted to the experimental aircraft association. The pilot was performing aerobatic maneuvers while the passenger was filming the event from the rear seat. During the pull-up portion of an immelman maneuver, the left wing failed and folded upwards. The pilot deployed a ballistic parachute to control the airplne's descent. As the parachute deployed, it became entangled with the engine propeller and was damaged and only partially inflated. The airplane descended and struck the ground at about 50 mph. The airplane and pilot did not qualify for the conditions of the ultralight regulation exemption, and the vehicle is considered to be an airplane.
Aircraft
- Registration
- UNREG
- Reported as
- Beierle Thunder Gull J (THUNDER GU)
- Category
- Ultralight, amateur-built
- Serial number
- 1
- Airframe hours
- 41
- Engine
- Bombardier ROTAX 503, 53 horsepower, reciprocating
- Damage
- Destroyed
- Flight
- Part 91
- Operator
- Mark Beierle
- Last inspection
- Unknown · January 2, 2000
- Departed
- NONE · Santa Margarita, CA
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 37
- Certificate
- Private
- Airplane ratings
- Single-engine land
- Medical
- Expired
- Seat
- Front
- Flight hours
- 3,000 total · 60 in the last 90 days · 41 in the last 30 days · 6 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Visibility
- 20 statute miles
- Lowest ceiling
- None
- Temperature
- 100 °F