- Date
- July 7, 1989, 19:15 local (Jul 8, 1989, 00:15 UTC)
- Place
- Guymon, OK
- Injuries
- 1 serious
- Damage
- Substantial damage
- Phase of flight
- Maneuvering
- Aircraft
- N788YGrumman G-164
- Weather
- Visual (VMC) · Day
- Status
- Completed · report September 5, 1991
- Report
- Approved by Office Director
- FAA report
- 19890707021169A
- Case key
- 22702
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
Failure of the upper right engine mount (firewall attach bolt) due to fatigue, and failure of the lower right mounting bolt for an unknown reason, which allowed overload failure of the two remaining mounting bolts and separation of the engine.
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
During pullup for a turnaround maneuver, the eng fell from the ag airplane. Control was lost & the airplane hit flat in a field. A post-acdnt investigation revealed the upper right eng mount (firewall attach bolt) had failed from fatigue. The lower right bolt had also failed prior to eng separation, but its facture surface was too badly damaged to verify the reason of failure. The upper left & lower left attach bolts were found necked down at their respective fractures from overload failure.
Aircraft
- Registration
- N788Y
- Reported as
- Grumman G-164
- Category
- Airplane
- Serial number
- 180
- Airframe hours
- 6,347
- Engine
- P&W R-985-AN-14B, 450 horsepower, reciprocating
- Damage
- Substantial damage
- Flight
- Aerial application · Part 137
- Operator
- Gray, Ronald W., doing business as Gray'S Spraying Service
- Registered owner
- Ronald W Gray
- Airworthiness certificate
- Special, Restricted (Special)
- Last inspection
- Annual · November 1, 1988 · 100 hours before
- Departed
- NONE · Hooker, OK
- Airport
- GUY
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
- 40
- Certificates
- Flight instructor, Commercial
- Airplane ratings
- Single-engine land, Multi-engine land
- Instrument ratings
- Airplane
- Medical
- Class 2, Valid Medical--no waivers/lim.
- Seat
- Center
- Flight hours
- 12,000 total · 2,500 in this make and model · 12,000 as pilot in command · 120 in the last 90 days · 40 in the last 30 days · 6 in the last 24 hours
Weather
- Conditions
- Visual (VMC) · Day
- Wind
- 80° at 7 knots
- Visibility
- 15 statute miles
- Lowest ceiling
- None
- Temperature
- 90 °F, dew point 52 °F
- Altimeter
- 30.00 inHg
- Observed at
- LBL, 29 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 N788Y · 1
Matched to the same aircraft by N-number and date.