# NTSB CHI05LA104: Weatherly 620B, N9026F, Downs, KS, April 20, 2005 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: April 20, 2005, 18:15 local (23:15 UTC) - Place: Downs, KS - Coordinates: 39.842498, -98.918609 - Nearby events: https://openairdocs.org/map.md?lat=39.8425&lon=-98.9186&mi=10 - Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report March 28, 2006 - Report: Approved by Office Director - Parties: FAA-Wichita FSDO - NTSB case key (mKey): 61379 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI05LA104 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/61379/pdf - Page: https://openairdocs.org/ntsb/CHI05LA104 ## Probable cause The loss of engine power due to the failure of the number two cylinder which was the result of the maintenance facility's failure to detect the fatigue crack in the number two cylinder during the engine overhaul. A factor to the accident was the soft field. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, maneuvering - aerial application - maintenance,inspection - not detected, other maintenance personnel (cause) - engine assembly,cylinder - fatigue (cause) - engine assembly,cylinder - failure (cause) - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, emergency landing - terrain condition - soft (contributing factor) - Gear collapsed, emergency landing ## Analysis The agricultural spray airplane sustained substantial damage during a forced landing to a farm field after a loss of engine power. The pilot reported that he was "pulling the airplane up into a right hand turn" at the end of a spray run when he heard a loud "bang" and the engine started to run "really rough." He executed a forced landing to a field. The landing gear broke off due to the soft field conditions. The engine was a 450 horsepower Pratt & Whitney R-985-14B engine. The engine was overhauled 43 hours prior to the accident. At overhaul, the engine had accumulated a total time of 7,027.1 hours. The engine logbook noted that AD 78-0807 was complied with. AD 78-0807 was effective May 2, 1978 for ultrasonic and visual inspections every 150 hours time in service to detect cracking and "to prevent cylinder head separation from the barrel." The logbook did not contain specific information on the previous histories of the installed cylinders. The inspection of the airplane revealed that the number 2 cylinder was broken at the third large cooling vent up from the bottom. The upper portion on the head assembly had separated from the sleeve. The National Transportation Safety Board's (NTSB) Materials Laboratory report noted that the fracture faces were covered by extensive and heavy combustion products and required extensive cleanings to reveal fracture details. Examinations of the fracture faces revealed features and topography indicative of a large area of fatigue progression. The fatigue area was on the aft side of the cylinder, biased toward the exhaust valve. Fracture face markings indicative of multiple fatigue initiation at the inner diameter threads along a wide arc of approximately 140 degrees. Progression was radial through the head with complete penetration over and arc of about 60 degrees centered in the fatigue region. The cylinder head was permanently marked with UT05, UT97, UT91, UT89, and UT89 stamped in the head near the intake port. The "UT" markings on the head are consistent with the markings required by AD 78-0807 and they denote five different ultrasonic inspections since 1989. ## Factual narrative On April 20, 2005, at 1815 central daylight time, a Weatherly 620B, N9026F, sustained substantial damage during a forced landing to a farm field about seven miles north of Downs, Kansas, after a loss of engine power. The commercial pilot received minor injuries. The 14 CFR Part 137 aerial application flight departed from a local field and was applying chemicals when the loss of engine power occurred. Visual meteorological conditions prevailed at the time of the accident. No flight plan was filed. The pilot reported that he was "pulling the airplane up into a right hand turn" at the end of a spray run when he heard a loud "bang" and the engine started to run "really rough." He executed a forced landing to a field. The pilot reported that the landing gear broke off due to the soft field conditions. The airplane was a Weatherly 620B, serial number 1639. The engine was a 450 horsepower Pratt & Whitney R-985-14B engine, serial number 20590. The engine was overhauled 43 hours prior to the accident on March 4, 2005. At overhaul, the engine had accumulated a total time of 7,027.1 hours. The engine logbook noted that AD 78-0807 was complied with. (AD 78-0807 was effective May 2, 1978 for ultrasonic and visual inspections every 150 hours time in service to detect cracking and "to prevent cylinder head separation from the barrel") The logbook did not contain specific information on the previous histories of the installed cylinders. The inspection of the airplane revealed that the number 2 cylinder was broken at the third large cooling vent up from the bottom. The upper portion on the head assembly had separated from the sleeve. The cylinder was sent to the National Transportation Safety Board's (NTSB) Material Laboratory for further examination. The NTSB Materials Laboratory report noted that the fracture faces were covered by extensive and heavy combustion products and required extensive cleanings to reveal fracture details. Examinations of the fracture faces revealed features and topography indicative of a large area of fatigue progression. The fatigue area was on the aft side of the cylinder, biased toward the exhaust valve. Fracture face markings indicative of multiple fatigue initiation at the inner diameter threads along a wide arc of approximately 140 degrees. Progression was radial through the head with complete penetration over and arc of about 60 degrees centered in the fatigue region. The cylinder head was permanently marked in various locations. They markings UT05, UT97, UT91, UT89, and UT89 were stamped in the head near the intake port. The "UT" markings on the head are consistent with the markings required by AD 78-0807 and they denote five different ultrasonic inspections since 1989. ## Aircraft - Registration: [N9026F](https://openairdocs.org/deregistered/N9026F-2005-06-13), registration cancelled 2005-06-13, S/N 1639, built 1996 (OpenAirDocs) - Reported make and model: Weatherly 620B - Registry model: [Weatherly 620B](https://openairdocs.org/model/weatherly-620b) (registry code 9630605) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 1639 - Airframe hours: 2319 - Engines: Pratt & Whitney R-985-14B 450 horsepower reciprocating - Damage: Substantial damage - Flight: Aerial application, Part 137 - Registered owner: AG Care By Air Inc. - Airworthiness certificate: Special, Restricted (Special) - Last inspection: Annual, March 1, 2005, 43 hours before - Departed: Private ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 40; injuries: minor; commercial; airplane ratings: single-engine land; medical: class 2, with waivers/limitations; last flight review March 1, 2004; seat: center; flight hours: 5,540 total, 3,201 in this make and model, 5,465 as pilot in command, 53 in the last 90 days, 53 in the last 30 days, 8 in the last 24 hours ## Weather - Conditions: Visual (VMC) - Wind: 160° at 4 knots - Visibility: 10 statute miles - Temperature: 81 °F, dew point 63 °F - Altimeter: 29.73 inHg - Observed at: RSL, 40 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 20050420007549A](https://openairdocs.org/incident/20050420007549A), Apr 20, 2005: Wthrly 620B, Downs, KS, Substantial damage. (-23) At approximately 1830 (local time) on 20 April 2005, during agricultural spraying operations, aircraft registration number N9026F developed an engine… 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.