NTSB Identification: LAX92LA252.
The docket is stored on NTSB microfiche number 47371.
Accident occurred Saturday, March 28, 1992 in NEWHALL, CA
Probable Cause Approval Date: 05/26/1993
Aircraft: BEECH B-35, registration: N8838A
Injuries: 2 Uninjured.

NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.

DURING A CROSS COUNTRY FLIGHT, THE OWNER/PILOT AND AN INSTRUCTOR PILOT WERE DESCENDING THROUGH A HOLE IN AN OVERCAST AT 135 KNOTS. THE V-TAIL DESIGNED AIRPLANE SUDDENLY EXPERIENCED 4 VIOLENT PITCH OSCILLATIONS. THE INSTRUCTOR PILOT, WHO WAS FLYING THE AIRPLANE, REDUCED AIRSPEED AND LEVELED THE WINGS. THIS ACTION STOPPED THE PITCH OSCILLATIONS. A POST FLIGHT INSPECTION REVEALED DAMAGE TO THE REAR FUSELAGE BULKHEAD, WRINKLING OF THE EMPENNAGE SKIN AND LOSS OF PAINT. THE AIRPLANE DID NOT HAVE ANY PLACARDED AIRSPEED RESTRICTIONS OR A VERIFICATION OF PROPER WEIGHT AND BALANCE CALCULATIONS. THE OWNER DID NOT PROVIDE ANY DOCUMENTATION OF COMPLIANCE WITH THE AD, OR OF PROPER BALANCING OF THE LEFT RUDDERVATOR THAT HAD BEEN PREVIOUSLY EXCHANGED AND INSTALLED. THE MANUFACTURER REPORTED THAT THE EMPENNAGE DAMAGE WAS TYPICAL OF RUDDERVATOR FLUTTER.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

IMPROPER RUDDERVATOR BALANCING THAT RESULTED IN RUDDERVATOR FLUTTER. CONTRIBUTING TO THE ACCIDENT WAS INSUFFICIENT MAINTENANCE INFORMATION TO ASSURE THAT AD COMPLIANCE AND ELEVATOR BALANCING WAS PERFORMED, AND AN INADEQUATE ANNUAL INSPECTION PROCEDURE THAT ASSURED PROPER MAINTENANCE COMPLIANCE.

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