NTSB Identification: MIA90FA190.
The docket is stored on NTSB microfiche number 42764.
Accident occurred Wednesday, September 26, 1990 in THORNTON, MS
Probable Cause Approval Date: 11/09/1992
Aircraft: Ayres S2R-T34, registration: N4017B
Injuries: 1 Fatal.
NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.
AIRPLANE EXPERIENCED SEPARATION OF RIGHT WING WHILE PULLING UP FROM AGRICULTURAL SPRAYING RUN. WING SEPARATED DUE TO FATIGUE FAILURE OF THE BOTTOM SPAR CAP WHICH WAS THE RESULT OF A HOLE BEING DRILLED INTO THE CAP. THE HOLE APPEARS TO HAVE BEEN DRILLED INTO THE CAP DURING INSTALLATION OF A WING MOUNTED AIR CONDITIONING COMPRESSOR, SIX YEARS AND 4,130 FLIGHT HOURS BEFORE THE FAILURE. THE AIR CONDITIONING UNIT WAS REMOVED 10 MONTHS LATER AND A PATCH WAS PLACED OVER THE AREA THE HOLE HAD BEEN DRILLED IN SPAR CAP. THE HOLE WOULD NOT HAVE BEEN VISIBLE DURING INSPECTION UNLESS MECHANIC REMOVED PATCH.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: THE IMPROPER DRILLING OF A HOLE IN THE SPAR CAP BY A MECHANIC RESULTING IN THE INITIATION OF FATIGUE CRACKING IN THE SPAR CAP AND SUBSEQUENT FAILURE OF THE SPAR CAP AND INFLIGHT SEPARATION OF THE WING.
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