- Date
- September 26, 1990, 09:14 local (14:14 UTC)
- Place
- Thornton, MS
- Injuries
- 1 fatal
- Damage
- Destroyed
- Phase of flight
- Maneuvering
- Aircraft
- N4017BAyres S2R-T34
- Weather
- Visual (VMC) · Day
- Status
- Completed · report November 9, 1992
- Report
- Approved by Office Director
- FAA report
- 19900926042439A
- Case key
- 32568
From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.
On this page
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.
Sequence of events
NTSB’s coding before 2008: each occurrence and phase of flight, and the causes and factors under it. The codes are defined in NTSB’s coding manual.
Analysis
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.
Aircraft
- Registration
- N4017B
- Reported as
- Ayres S2R-T34
- Category
- Airplane
- Serial number
- T34-002
- Airframe hours
- 5,592
- Engine
- P&W PT6A-34AG, 783 horsepower, turbo prop
- Damage
- Destroyed
- Flight
- Aerial application · Part 137
- Registered owner
- George Clanton Dusting Sprayin
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · May 7, 1990 · 491 hours before
- Departed
- 87I · Yazoo City, MS
Matched to the registry by N-number and the event date; the registry’s history has gaps, so older matches can be wrong. Compare the reported make and model.
Flight crew
As NTSB recorded them. NTSB leaves out names.
- Role
- Pilot
- Age
- 66
- Certificate
- Commercial
- Airplane ratings
- Single-engine land
- Medical
- Class 2, Valid Medical--w/ waivers/lim
- Seat
- Front
- Toxicology
- Performed
- Flight hours
- 27,500 total · 3,200 in this make and model · 500 in the last 90 days · 125 in the last 30 days · 1 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 190° at 5 knots
- Visibility
- 7 statute miles
- Lowest ceiling
- None
- Temperature
- 64 °F, dew point 54 °F
- Altimeter
- 30.00 inHg
- Observed at
- GWO, 25 nm away
FAA reports on this event · 1
The FAA’s own accident and incident reports, matched to the aircraft by N-number and date.
Other investigations on N4017B · 1
Matched to the same aircraft by N-number and date.