# NTSB CHI95LA258: Air Tractor AT-401, N4543F, Aurora, NE, August 4, 1995 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: August 4, 1995, 09:45 local (14:45 UTC) - Place: Aurora, NE - Coordinates: 40.859802, -97.999908 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.8598&lon=-97.9999&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 4, 1995 - Report: Approved by Office Director - NTSB case key (mKey): 9976 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI95LA258 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/9976/pdf - Page: https://openairdocs.org/ntsb/CHI95LA258 ## Probable cause the cracked engine assembly that caused the power loss during a critical phase of flight. Factors associated with this accident were the restricted airplane performance due to the power loss, the airplane's altitude was too low, and remedial action, by, the pilot, that would lead to an uneventful forced landing was not possible. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, maneuvering - aerial application - In flight collision with object, emergency landing - In flight collision with terrain/water, descent - uncontrolled ## Analysis AT THE BEGINNING OF THE PILOT'S SWATH RUN HE NOTICED WHITE SMOKE COMING FROM THE RIGHT SIDE OF THE ENGINE. HE SAID HE DISCONTINUED THE RUN AND TURNED BACK TOWARD HIS HOME AIRPORT. JUST AS THE AIRPLANE LEVELED OUT FROM ITS TURN THE PILOT SAID THE ENGINE LOST MOST OF ITS POWER. THE PILOT SAID HE HEADED THE AIRPLANE FOR A PASTURE BUT WAS UNABLE TO GLIDE TO IT. THE AIRPLANE NOSED OVER SHORTLY AFTER ITS WHEELS CONTACTED THE CORN, COMING TO REST ON THE GROUND. EXAMINATION OF THE ENGINE REVEALED THE NUMBER 4 CYLINDER'S EXHAUST TOWER WAS CRACKED WHERE THE ROCKER ARM SHAFT WENT THROUGH THE CYLINDER HEAD. THE OWNER/MECHANIC OF THE AIRPLANE SAID THE CONDITION RESULTING FROM THE DAMAGED EXHAUST TOWER PREVENTS THE CYLINDER'S EXHAUST VALVE FROM OPENING. THE RESULT OF THE EXHAUST VALVE NOT OPENING CREATES A BLOW BACK CONDITION THAT AFFECTS THE OTHER CYLINDERS. THE END RESULT, ACCORDING TO THE OWNER, IS THAT THE ENGINE WILL LOSE MOST OF ITS POWER. THIS WAS CONFIRMED BY THE FAA PRINCIPAL MAINTENANCE INSPECTOR WHO CONDUCTED THE ENGINE EXAMINATION. ## Factual narrative On August 4, 1995, at 0945 central daylight time (cdt), an Air Tractor AT-401, N4543F, registered to Aurora Aircraft, Incorporated, of Aurora, Nebraska, and piloted by an airline transport rated pilot, was substantially damaged during a forced landing following a pilot reported total loss of power. The pilot said the power loss occurred during the beginning of a crop spray run. The 14 CFR Part 137 aerial application flight was not operating on a flight plan. Visual meteorological conditions prevailed at the time of the accident. The pilot reported no injuries. The flight departed Aurora, Nebraska, at 0920 cdt. The pilot said he had begun a swath run when he noticed white smoke coming from the right side of the engine. He said he stopped the swath run and turned back toward the airport. After turning toward the airport the pilot said the engine began to run "...very rough... ." Shortly after the roughness began he said the engine lost most of its power. Upon experiencing the power loss, the pilot said he headed toward a pasture. He said he was unable to glide to the pasture and had to land in a corn field. The airplane nosed over when the tires contacted the corn. A Federal Aviation Administration Principal Maintenance Inspector (PMI) represented the NTSB on-scene. The PMI said the engine examination revealed the number four cylinder's exhaust tower was cracked where the rocker arm shaft went through the head. The owner/mechanic of the airplane stated the cracked exhaust tower causes the cylinder's exhaust valve not to open. This in turn causes a "blow back" condition to exist for the other cylinders. The "blow back" causes' the engine to loose most of its power, according to the airplane owner. The PMI confirmed this information. ## Aircraft - Registration: [N4543F](https://openairdocs.org/deregistered/N4543F-2000-05-11), registration cancelled 2000-05-11, S/N 401-0787 (OpenAirDocs) - Reported make and model: AIR TRACTOR AT-401 - Registry model: [Air Tractor AT-401](https://openairdocs.org/model/air-tractor-at-401) (registry code 0390204) (OpenAirDocs) - Category: Airplane - Serial number: 401-0787 - Airframe hours: 1439 - Engines: P&W R-1340-AN-1 600 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: Aurora Aircraft, Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, April 10, 1995, 187 hours before - Departed: AUH, NE ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: center; flight hours: 10,220 total, 1,600 in this make and model, 9,750 as pilot in command, 190 in the last 90 days, 100 in the last 30 days, 12 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 100° at 8 knots - Lowest ceiling: 1,100 ft broken - Temperature: 75 °F, dew point 70 °F - Altimeter: 30.00 inHg - Observed at: GRI, 15 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 (OpenAirDocs). - [Accident 19950804021859A](https://openairdocs.org/incident/19950804021859A), Aug 4, 1995: Airtrc AT401, Aurora, NE, Substantial damage. Engine smoke on spray run. Pulled up. Engine quit. Nosed over landing. NR4 cylinder cracked jammed valve. ## Other investigations on N4543F (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB CHI98LA355](https://openairdocs.org/ntsb/CHI98LA355), Aug 28, 1998: Air Tractor AT-401 (N4543F), N. Ottawa Twp., MN, destroyed. Probable cause: A loss of engine power due to a worn piston ring. A related factor was the owner exceeded the manufacturer's recommended engine overhaul. From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.