FTW97LA169

NTSB accident investigation · Air Tractor AT-400 · Fluvanna, TX · April 19, 1997

Accident · No injuriesLimited investigationFinal report
Date
April 19, 1997, 14:00 local (19:00 UTC)
Place
Fluvanna, TX
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Maneuvering
Aircraft
N73127Air Tractor AT-400
Weather
Visual (VMC) · Day
Status
Completed · report August 25, 1997
Report
Approved by Office Director
FAA report
19970419007399A
Case key
20204

From the NTSB’s public API. By law, NTSB reports can’t be used as evidence in lawsuits over the accident.

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Probable cause

The loss of engine power due to the failure of the reduction gear box. A factor was the lack of suitable terrain for the forced landing.

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.

Loss of engine power(total) - mech failure/malfManeuvering - aerial application
Reduction gear assy - failure,totalCause
Turbine assembly,shaft bearing - sheared
Turbine assembly - overspeed
Turbine assembly,turbine blade - disintegrated
Forced landingEmergency descent/landing
In flight collision with terrain/waterEmergency landing
Terrain condition - none suitableFactor
Terrain condition - rough/uneven

Analysis

The pilot was performing a swath run when he felt a vibration, and then the engine lost power. A forced landing was initiated to a plowed field. During the landing sequence, the left main landing gear separated from the fuselage, and the right wing spar was bent upward. A teardown inspection of the airplane's engine revealed that the reduction gear box failed and sheared the drive shaft. According to the FAA inspector, 'This failure allowed a turbine over speed to the point that the turbine blades separated from the wheel causing a contained catastrophic failure.'

Factual narrative

On April 19, 1997, at 1400 central daylight time, an Air Tractor AT-400 agricultural airplane, N73127, registered to and operated by Benny White Flying Service, Inc., as a Title 14 CFR Part 137 aerial application flight, was substantially damaged during a forced landing following a loss of engine power near Fluvanna, Texas. The commercial pilot was not injured. Visual meteorological conditions prevailed, and a flight plan was not filed for the local flight that originated from a private airstrip near Lamesa, Texas.

According to the pilot, he was performing a swath run when he felt a vibration, followed by a loss of engine power. A forced landing was initiated to a plowed field. During the landing sequence, the left main landing gear separated from the fuselage, and the right wing spar was bent upward.

Examination of the PT6A-27 engine by a mechanic and the FAA inspector revealed that the turbine disc was missing approximately half of its blades. The engine was sent to Dallas Airmotive in Dallas, Texas, for further examination. On May 22, 1997, a teardown inspection revealed that the reduction gear box failed and sheared the drive shaft. According to the FAA inspector, "It was impossible to determine which part failed first. This failure allowed a turbine over speed to the point that the turbine blades separated from the wheel causing a contained catastrophic failure."

According to the operator, the engine had accumulated a total of 2,430 hours since new, with approximately 1,300 hours since last overhaul.

Aircraft

Registration
N73127
Reported as
Air Tractor AT-400
Category
Airplane
Serial number
301-0667
Airframe hours
3,562
Engine
P&W PT6A-27, 680 horsepower, turbo prop
Damage
Substantial damage
Flight
Aerial application · Part 137
Registered owner
Benny White Flying Svc Inc
Airworthiness certificate
Special, Restricted (Special)
Last inspection
Annual · March 3, 1997 · 86 hours before
Departed
NONE · Lamesa, TX

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
44
Certificate
Commercial
Airplane ratings
Single-engine land
Medical
Class 2, Valid Medical--w/ waivers/lim
Seat
Front
Flight hours
10,000 total · 320 in this make and model

Weather

Conditions
Visual (VMC) · Day
Wind
Calm
Visibility
10 statute miles
Lowest ceiling
2,300 ft overcast
Temperature
63 °F, dew point 54 °F
Altimeter
29.00 inHg
Observed at
ABI, 157 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 N73127 · 1

Matched to the same aircraft by N-number and date.