NTSB Identification: CHI92DCD07.
The docket is stored on NTSB microfiche number 48114.
Accident occurred Wednesday, July 01, 1992 in EARLHAM, IA
Probable Cause Approval Date: 09/14/1993
Aircraft: BERNARD W. RESNIK ACRO-SPECIAL, registration: N79WA
Injuries: 1 Serious,1 Minor.

THE HOMEBUILT ACCIDENT AIRPLANE LOST ENGINE POWER DURING INITIAL CLIMB FROM TAKEOFF. IT COLLIDED WITH TREES AND TERRAIN DURING A FORCED LANDING. THE PILOT DESCRIBED HOW HE HAD BEEN FLYING ABOUT 45 MINUTES AND HAD DONE TWO LANDINGS AND TAKEOFFS. DURING THE THIRD TAKEOFF THE AIRPLANE HAD CLIMBED ABOUT 75 TO 100 FEET WHEN THE ENGINE LOST POWER. EXAMINATION OF THE CARBURETOR AIR BOX REVEALED A FLAPPER VALVE IN THE AIR BOX HAD BROKEN. THE VALVE PLATE WAS FREE TO MOVE ABOUT IN THE SPACE BETWEEN THE SHAFT AND THE CARBURETOR AIR INTAKE. THE PLATE HAD BEEN SECURED TO THE SHAFT WITH TWO SPOT WELDS. THE SURFACE OF THE BROKEN WELDS APPEARED DULL EXCEPT FOR A SMALL PORTION ON ONE WELD WHERE THE BREAK APPEARED SHINY. THE CARBURETOR AIR BOX HAD BEEN PURCHASED FROM AN AIRCRAFT SALVAGE OPERATOR FOR INSTALLATION ON THE AIRPLANE.

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

A LOSS OF TOTAL ENGINE POWER WHEN A FAILED FLAPPER VALVE IN THE AIR BOX BLOCKED THE FLOW OF AIR THROUGH THE CARBURETOR THROAT.

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