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Aviation safety reports, made easier to study

NTSB Reports is an independent research and search tool for public aviation accident and incident records. It brings NTSB aviation reports, structured fields, docket files, extracted figures, photos, videos, and update history into one searchable interface.

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September 26, 1990 · Ayres S2R-T34 · N4017B

Thornton, MS

Overview

Report Status
Probable Cause
Event Type
Accident
Date
September 26, 1990
Injury Outcomes
1 injury (1 fatality)
Location
Thornton, MS
Aircraft
Ayres S2R-T34
Tail Number
N4017B
Injuries
Fatal
Aircraft Damage
Destroyed
NTSB Number
MIA90FA190

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.

NTSB Probable Cause

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.

Full Narrative

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.

Flight

Event TypeAccident
Event Time09:14 CDT
Nearest Airport0nm N
Runway0
Flight Plan FiledNone
Aircraft FireNo
Aircraft ExplosionNo

Aircraft

AircraftAyres S2R-T34
Tail NumberN4017B
Aircraft CategoryAir
DamageDestroyed
Operating RulePart 137
Engines1
Engine TypeTurboprop
Engine DetailsP&W · PT6A-34AG · Turboprop · 783
Seats1

People & Injuries

Injury Summary1 injury (1 fatality)
Fatal1
Serious0
Minor0
Uninjured0
Total1
Crew 1Age 66 · Second Class

Conditions

ConditionsVMC
LightDaylight
Wind190° @ 5 kt
Visibility7 sm
CeilingNone
Temperature / Dew Point64 F / 54
Altimeter30.00 inHg
Observation Time13:52
Weather SourceWFAC

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Appendix: Source Data