# NTSB CHI07LA108: Swearingen SA-226T, N125WG, Wheeling, IL, April 11, 2007 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 11, 2007, 11:15 local (16:15 UTC) - Place: Wheeling, IL - Coordinates: 42.1141666666667, -87.9013888888889 - Nearby events: https://openairdocs.org/map.md?lat=42.1142&lon=-87.9014&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 5 uninjured - Status: Completed, report February 28, 2008 - Report: Approved by Office Director - Parties: FAA-DuPage FSDO - NTSB case key (mKey): 65660 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI07LA108 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/65660/pdf - Page: https://openairdocs.org/ntsb/CHI07LA108 ## Probable cause Partial failure of the left engine propeller governor during the takeoff ground roll. Factors included that directional control was not possible by the pilot which subsequently led to a collision with an airport sign. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of control - on ground/water, takeoff - roll/run - directional control - not possible, pilot in command (contributing factor) - propeller system/accessories,governor - failure,partial (cause) - On ground/water encounter with terrain/water, takeoff - aborted - terrain condition - grass - terrain condition - snow covered - On ground/water collision with object, takeoff - aborted - object - sign (contributing factor) ## Analysis The pilot reported that upon reaching approximately 75 knots during the takeoff roll, he felt a surge from the left engine. He noted that the "surging continued and positive directional control could not be regained," at which point he closed the throttles and elected to abort the takeoff. The pilot attempted to maintain directional control by using differential braking and rudder inputs. The airplane subsequently departed the left side of the runway and impacted an airport sign, causing the nose landing gear to collapse, before coming to rest. Post accident testing of the left propeller governor unit revealed that the component pressure gain was approximately one-half of the manufacturer's specification, resulting in the unstable engine operation. ## Factual narrative On April 11, 2007, at 1115 central daylight time, a Swearingen SA-226T, N125WG, piloted by an airline transport pilot, was substantially damaged during an aborted takeoff on runway 16 (5,000 feet by 150 feet, asphalt) at Chicago Executive Airport (PWK), Wheeling, Illinois. Instrument meteorological conditions prevailed at the time of the accident. The business flight was being conducted under 14 CFR Part 91 on an instrument flight rules (IFR) flight plan. The pilot and four passengers on-board were not injured. The flight was originating at the time of the accident and had an intended destination of Shreveport Regional Airport (SHV), Shreveport, Louisiana. The pilot reported that upon reaching approximately 75 knots during the takeoff roll, he felt the left engine surge. He noted that the "surging continued and positive directional control could not be regained," at which point he closed the throttles and elected to abort the takeoff. The pilot attempted to maintain directional control by using differential braking and rudder inputs. The airplane subsequently departed the left side of the runway and impacted an airport sign, causing the nose landing gear to collapse, before coming to rest. Post accident testing of the left engine propeller governor indicated that it did not meet the manufacturer's requirements. Specifically, the pressure gain across the unit was approximately one-half that required by manufacturer's specifications. Bench testing revealed that a shaft input speed of approximately 80 RPM was required to provide a pressure increase of 150 pounds-per-square inch (psi). The specification required an input speed of between 20 and 40 RPM in order to obtain the 150 psi pressure increase. Subsequent testing and teardown inspection of the governor unit revealed that the flyweight toe extensions were worn. This altered the position of the flyweights during operation and reduced the component pressure gain. Aircraft maintenance records indicated that an overhaul of the governor unit was completed on November 22, 2000. It had accumulated approximately 913 hours time in service at the time of the accident. Detailed records of the overhaul were not available. According to the component manufacturer, the flyweights are not normally replaced during overhaul. However, the flyweights are replaced when wear is observed. The manufacturer's recommended overhaul interval was 3,500 hours. A representative of the propeller manufacturer stated that a governor unit exhibiting a low gain condition, such as the unit on the accident airplane, may cause unstable engine operation such as the surging reported by the accident pilot. ## Aircraft - Registration: [N125WG](https://openairdocs.org/deregistered/N125WG-2018-05-30), registration cancelled 2018-05-30, S/N T250, built 1974 (OpenAirDocs) - Reported make and model: Swearingen SA-226T - Registry model: [Swearingen SA-226T](https://openairdocs.org/model/swearingen-sa-226t) (registry code 8780122) (OpenAirDocs) - Registry engine: [AiResearch TPE331 series](https://openairdocs.org/engine/airesearch-tpe331-series) (registry code 01514, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: T250 - Airframe hours: 6027 - Engines: Garrett TPE-331-10UA 840 horsepower turbo prop; Garrett TPE-331-10UA 840 horsepower turbo prop - Damage: Substantial damage - Flight: Executive/Corporate, Part 91 - Registered owner: Good Aviation LTD - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, September 1, 2006 - Departed: PWK, Wheeling, IL - Destination: SHV, Shreveport, LA - Flight plan: IFR - Airport: PWK, Chicago Executive, runway 16, 5,000 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; injuries: none; airline transport, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review October 1, 2005; seat: left; flight hours: 6,800 total, 550 in this make and model, 6,750 as pilot in command, 67 in the last 90 days, 23 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 90° at 11 knots, gusting 26 - Visibility: 0.75 statute miles - Lowest ceiling: 700 ft broken - Temperature: 34 °F, dew point 32 °F - Altimeter: 29.53 inHg - Observed at: PWK ## 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 20070411006579A](https://openairdocs.org/incident/20070411006579A), Apr 11, 2007: Swrngn SA226T, Chicago/Wheeli, IL, Substantial damage. (-23) Weather at the time of the accident was low overcast and snow with winds 090@11G26. The takeoff roll on runway 16 was normal until at a speed of… ## Other investigations on N125WG (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 CEN16WA179](https://openairdocs.org/ntsb/CEN16WA179), Apr 26, 2016: Swearingen SA 226T (N125WG), Andorra, Lleida, Spain, Spain, substantial damage 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.