LAX97LA182

NTSB accident investigation · Ayres S2R-T-34 · Tonopah, AZ · May 8, 1997

Accident · No injuriesLimited investigationFinal report
Date
May 7, 1997, 20:25 local (May 8, 1997, 03:25 UTC)
Place
Tonopah, AZ
Injuries
1 uninjured
Damage
Substantial damage
Phase of flight
Enroute
Aircraft
N4011GAyres S2R-T-34
Weather
Visual (VMC) · Night/bright
Status
Completed · report May 4, 1998
Report
Approved by Office Director
FAA report
19970507012869A
Case key
29789

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 failure of the power turbine due to an overtemperature condition created by an improperly adjusted fuel control. A factor in the accident was the tripped circuit breaker which prevented the wing lights from operating during the forced night 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/malfCruise
Fuel system,fuel control - excessive flow/outputCause
Maintenance,adjustment - improperCompany maintenance personnelCause
Turbine assembly - overtemperatureCause
Turbine assembly - failure,total
Forced landingEmergency descent/landing
Light condition - bright nightFactor
Electrical system,circuit breaker - popped/trippedFactor
Landing light(s) - inoperativeFactor
On ground/water encounter with terrain/waterLanding - roll
Terrain condition - ditch
Landing gear - overload

Analysis

The pilot was en route back to his landing strip after night spraying when the aircraft lost engine power. He also saw flames and debris coming from the exhaust stacks. The circuit breaker popped when he attempted to turn on the wing lights so he continued the approach without lights. During rollout, the aircraft struck an unseen irrigation ditch and the gear collapsed. An inspection showed evidence of heat and blade damage to the power turbine. The fuel control adjustment was found in the full rich position. There was no evidence of FOD to the compressor rotor and stator assemblies. The engine had a hot section inspection as a result of a previous sudden engine stoppage incident.

Factual narrative

On May 7, 1997, at 2025 hours mountain standard time an Ayers S2R-T-34, N4011G, experienced a power loss and made an off-airport, night forced landing near Tonopah, Arizona. The aircraft sustained substantial damage; however, the pilot, the sole occupant, was not injured. The aircraft was being operated as an agricultural flight by Pierce Aviation under 14 CFR Part 137 when the accident occurred. The flight originated in Buckeye, Arizona, at 1930. Visual meteorological conditions prevailed at the time and no flight plan was filed.

The pilot said he had completed a routine spraying application and was en route back to an agricultural strip when the aircraft experienced a total loss of engine power. At the time of the power loss, he saw flames and debris being emitted from the engine exhaust stacks.

In response to the power loss, he moved the power lever to idle, moved the fuel control to the "off" position, and feathered the propeller. He established the aircraft in a glide toward an area of open farm land and shut off all unnecessary electrical equipment.

The 70 amp circuit breaker popped when he attempted to adjust the main wing lights for landing. His attempts to reset the breaker were unsuccessful and he was forced to continue the approach without the aid of wing lights.

After the landing and early in the rollout, the aircraft struck an irrigation ditch and the gear collapsed. The aircraft then slid an additional 150 feet before coming to rest. The pilot notified company personnel with a hand-held radio and they responded to his location.

According to an Federal Aviation Administration (FAA) airworthiness inspector who examined the aircraft, the engine did not exhibit any external damage; however, while inspecting the exhaust port, he observed evidence of damage to the power turbine. His attempts to rotate the turbine wheel by hand were unsuccessful. The fuel control adjustment was in the full rich position.

The engine was removed from the aircraft and shipped to Airforce Turbine Service in Tynan, Texas, for a teardown inspection. The teardown was observed by an FAA airworthiness inspector from the San Antonio, Texas, Flight Standards District Office.

The inspector reported that there was evidence of heat and blade damage to the power turbine, including the inlet guide vane ring. The damage was localized in the power section and there was no evidence of FOD to the three compressor rotor and stator assemblies.

A review of the aircraft maintenance records revealed that the engine had undergone a hot section inspection on June 26, 1996, as a result of a sudden engine stoppage incident. At that time, the aircraft had a total of 13,536 hours.

Aircraft

Registration
N4011G
Reported as
Ayres S2R-T-34
Category
Airplane
Serial number
6020
Airframe hours
14,245
Engine
P&W PT6-A-34AG, 750 horsepower, turbo prop
Damage
Substantial damage
Flight
Aerial application · Part 137
Registered owner
Pierce Aviation
Airworthiness certificate
Special, Restricted (Special)
Departed
Buckeye, AZ

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
52
Certificate
Airline transport
Airplane ratings
Single-engine land, Multi-engine land
Instrument ratings
Airplane
Medical
Class 2, Valid Medical--w/ waivers/lim
Seat
Center
Flight hours
20,380 total · 10,699 in this make and model

Weather

Conditions
Visual (VMC) · Night/bright
Wind
280° at 8 knots
Visibility
10 statute miles
Lowest ceiling
None
Temperature
93 °F
Altimeter
29.00 inHg
Observed at
PHX, 56 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.