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ASN Wikibase Occurrence # 41021
Last updated: 8 February 2021
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Date:04-AUG-1995
Time:09:26
Type:Peregrine PJ-2
Owner/operator:Fox Aircraft
Registration: N62PJ
C/n / msn: 001
Fatalities:Fatalities: 1 / Occupants: 1
Other fatalities:0
Aircraft damage: Written off (damaged beyond repair)
Category:Accident
Location:Minden, NV -   United States of America
Phase: Approach
Nature:Unknown
Departure airport:(MEV)
Destination airport:
Investigating agency: NTSB
Narrative:
THE AIRCRAFT WAS ON A DEVELOPMENTAL FLIGHT TEST PROGRAM. THE PILOT REPORTED A SPLIT FLAP SITUATION DURING THE GO-AROUND. WITNESSES OBSERVED THE AIRPLANE TURN ONTO A LEFT CROSSWIND, THEN BEGIN A RIGHT ROLL TO GROUND IMPACT. A PIN IN THE LEFT FLAP DRIVE WAS FOUND SHEARED. THE PIN WAS EXAMINED AND FOUND TO MEET THE MANUFACTURER'S MATERIAL SPECIFICATIONS. IT WAS DETERMINED THE PIN HAD FAILED DUE TO OVERLOAD SHEAR FORCES WHILE TORSIONAL AND AXIAL LOADS WERE APPLIED. THE FLAPS ARE DRIVEN BY A SINGLE ELECTRIC MOTOR WHICH ROTATES TWO INDEPENDENT FLEXIBLE DRIVE SHAFTS THAT ACTUATE THE RIGHT AND LEFT FLAP PANELS. THE SHEARED PIN BROKE THE CONTINUITY OF THE LEFT FLAP PANEL DRIVE STOPPING THE FLAP PANEL WHILE THE RIGHT FLAP PANEL WOULD CONTINUE TO EXTEND OR RETRACT. THERE WAS NO SYSTEM OR MECHANISM IN THE AIRPLANE THAT DETECTED AN ASYMMETRICAL FLAP CONDITION. TESTS OF THE FLAP SYSTEM REVEALED THE ELECTRICAL MOTOR IN THE FLAP SYSTEM WAS CAPABLE OF SHEARING THE PIN BEFORE A CIRCUIT BREAKER WOULD INTERRUPT ELECTRICAL POWER TO THE MOTOR. CAUSE: a failure of the wing flap control system due to inadequate design, which led to an asymmetrical flap deployment during a critical flight condition and in-flight loss of control. A related factor was the lack of a split-flaps warning system.

Sources:

NTSB: http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001207X04277


Revision history:

Date/timeContributorUpdates
24-Oct-2008 10:30 ASN archive Added
21-Dec-2016 19:23 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]

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