# NTSB WPR22FA188: Cessna 172F, N5532R, Show Low, AZ, May 26, 2022 - Type: NTSB accident investigation - Classification: Accident · Fatal · Class 3 · Field · Final report - Date: May 25, 2022, 17:50 local (May 26, 2022, 00:50 UTC) - Place: Show Low, AZ - Coordinates: 34.247904, -110.02313 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.2479&lon=-110.0231&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Fatal - Injuries: 2 fatal - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Textron Aviation, FAA - NTSB case key (mKey): 105133 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR22FA188 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/105133/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=105133 - Page: https://openairdocs.org/ntsb/WPR22FA188 ## Probable cause The pilot’s improper leaning of the engine during an extended period of time, which caused an exhaust valve to become stuck and led to the partial loss of engine power during the accident flight. Contributing to the accident was the pilot’s decision to attempt a second takeoff without having the engine further examined. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Knowledge: knowledge of procedures](https://openairdocs.org/ntsb-findings/02032010): Personnel issues › Experience/knowledge · Pilot (probable cause); cases with it: [Cessna 172F, 2 cases](https://openairdocs.org/ntsb-findings/02032010/cases.md?model=2072414), [All aircraft, 41 cases](https://openairdocs.org/ntsb-findings/02032010/cases.md) - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Incorrect use/operation (probable cause); cases with it: [Cessna 172F, 3 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=2072414), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Cessna 172F, 8 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=2072414), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Cessna 172F, 4 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2072414), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Cessna 172F, 9 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=2072414), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot and passenger were departing on a personal flight. Witnesses observed the airplane attempt to take off, but the takeoff was aborted, and the airplane was then taxied back to the approach end of the runway so that the pilot could perform an engine run-up. The witnesses stated that the engine was “sputtering” and “sounded bad” during the takeoff and the taxi to the run up area. The pilot subsequently attempted a second takeoff. The airplane remained at a low altitude, began a left turn toward the downwind pattern, and then “sank” out of sight behind a ridgeline before impacting terrain. A pilot witness stated that the pilot had “milked it [off the runway], set it back down, and then milked it off [the runway] again.” This witness also described the engine as “running rich, like it was bogged down” during the second takeoff. Postaccident examination of the engine found that the No. 4 engine cylinder exhaust valve was stuck due to a buildup of material that enlarged the overall diameter of the valve’s stem. Examination of the valve stem deposits showed indications of an organic compound that was consistent with deposits of unburned fuel. The stuck valve led to a partial loss of power during the accident takeoffs. The accident pilot reported to another pilot that there had been previous engine problems that had been identified as stuck valves. The accident pilot also reported that he ”never leaned the engine” and that he had little to-no training on how to lean the engine. The partial loss of engine power that resulted from the No. 4 cylinder exhaust valve becoming stuck was likely due to the pilot's improper leaning of the engine over an extended period. Excessively rich mixtures can lead to a buildup of unburned hydrocarbons, which can foul engine components with deposits. The accident could likely have been avoided if the pilot had the airplane examined by maintenance personnel before attempting the second takeoff. ## Factual narrative The engine was overhauled on April 29, 2016, and six new Continental 658319A1 cylinders were installed. On October 28, 2020, the pilot purchased the accident airplane. On April 26, 2021, the No. 2 cylinder was removed due to a stuck exhaust valve. The work order for the cylinder repair did not specify a reason for the stuck valve. The valve was repaired, and the cylinder was reinstalled 4 days later. At that time, the engine had accumulated 169.32 hours of tachometer time. The engine logbook contained entries for an annual inspection on September 29, 2021, and an oil change on February 19, 2022. The tachometer displayed 276.79 hours at the time of the accident. The pilot’s supervisor, who was also a pilot and had flown with the accident pilot, thought an exhaust valve also became stuck sometime between January 16 and February 27, 2022, and that the pilot had difficulty finding a mechanic to fix the stuck valve. The supervisor further stated that he explained to the pilot the procedure for resolving the stuck valve, but he did not know if the pilot attempted that procedure himself or found a mechanic to perform the work. The pilot’s supervisor also stated that, during one flight with the accident pilot, he (the supervisor) was leaning the engine when the pilot stated that he “never leaned the engine” and “didn’t need to lean the engine below 3000 feet.” The pilot indicated that he had “little or no training” on leaning the engine. On May 25, 2022, about 1750 mountain standard time, a Cessna 172F airplane, N5532R, was substantially damaged when it was involved in an accident near Show Low Regional Airport (SOW), Show Low, Arizona. The pilot and passenger were fatally injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. On the morning of the accident, the pilot flew from Ak-Chin Regional Airport (A39), Maricopa, Arizona, to Falcon Field Airport (FFZ), Mesa, Arizona, to pick up the passenger and then departed for SOW. The flight arrived at SOW about 0900, and the airplane occupants spent most of the day away from the airport. A witness stated the pilot and passenger returned to the airport in the late afternoon. The witness assisted them with refueling the airplane at the self-service fuel pump and stated that both wing tanks were filled to the bottom of the filler neck. Witnesses at SOW observed the airplane attempt to take off from runway 25 about 1745. The airplane became airborne two or three times during the first attempted takeoff but did not climb very high. One witness stated that the airplane touched down, “got squirrely,” and almost departed the end of the runway. Another witness stated that the airplane slid sideways and that the engine “did not sound healthy.” Another witness stated that the engine was “sputtering.” The pilot then taxied the airplane back to the approach end of runway 25 and performed a run-up. A witness stated the engine “sounded bad” when the airplane was taxiing. Thepilot then attempted a second takeoff. According to a witness who was also a pilot, the accident pilot “milked it off [the runway], set it back down, and then milked it off [the runway] again.” The witness stated that the engine was “running rich, bogged down” during the second takeoff. The airplane remained at a low altitude, began a left turn toward the downwind pattern, and then “sank.” Another witness stated that, during the left turn, the airplane descended out of sight behind a ridgeline. The airplane subsequently impacted terrain in an open field about 1 mile southwest of the departure end of runway 25. The airplane impacted the edge of a stream in an open field. The wreckage was oriented along a 075° heading. The accident site and debris field were confined to the initial impact point. Forward of the empennage, the fuselage was bent downward. All flight control surfaces were attached to the airplane, and flight control continuity was established to the cockpit controls. The engine was pushed aft, and it protruded into the cockpit. The engine remained attached to the airframe. Engine control continuity was not established due to impact damage. The carburetor was impact separated from the engine. The mixture control at the carburetor was observed in the lean position. Valve train continuity and thumb compression/suction were obtained on all cylinders except for cylinder No. 4. Cylinder No. 4 was removed, and the exhaust valve was observed to be stuck in the open position. The magneto leads for the bottom spark plugs of cylinders Nos. 2, 4, and 6 exhibited impact damage. Both magnetos were removed, and the magneto leads were cut near the housing. The removed magnetos were rotated by hand, and spark was observed on all the leads. The bottom spark plug of cylinder No. 4 exhibited carbon buildup (see figure 1), and the cylinder contained debris (see figure 2). Figure 1. No. 4 cylinder lower spark plug (Source: Textron Aviation). Figure 2. No. 4 cylinder interior and debris (Source: Textron Aviation). The No. 4 cylinder was disassembled, and the exhaust valve stem was mostly covered in carbon buildup (see figure 3). The cylinder and associated exhaust valve components were sent to the National Transportation Safety Board (NTSB) Materials Laboratory for further examination. Figure 3. No. 4 cylinder exhaust valve. Visual examination of the exhaust valve stem found that the 0.6 to 0.7 inches of the exhaust valve stem (from the seat) exhibited deposits and that the deposits that were 0.5 inches from the seat exhibited a dark brown color with a dull luster. The other 0.1 to 0.2 inches of deposits exhibited a black color that was more reflective. Dark brown and orange-yellow deposits were present over the exhaust valve head. The deposits exhibited a flaky layered morphology that increased the overall diameter of the stem (see figure 4). Figure 4. Exhaust valve deposits. The deposits on the exhaust valve stem and valve seat surface were furtherexamined. They showed indications of a single-chained polymer-like organic compound, consistent with deposits of unburned fuel. ## Aircraft - Registration: [N5532R](https://openairdocs.org/aircraft/N5532R), registered now, S/N 17253113, built 1965 (OpenAirDocs) - Reported make and model: CESSNA 172F - Registry model: [Cessna 172F](https://openairdocs.org/model/cessna-172f) (registry code 2072414) (OpenAirDocs) - Registry engine: [Continental 0-300 series](https://openairdocs.org/engine/continental-0-300-series) (registry code 17022, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 17253113 - Year built: 1965 - Airframe hours: 6840.62 - Engines: Continental Motors O300D(6) 145 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, September 29, 2021, 84 hours before - Airport: SOW, Show Low Regional Airport, runway 25, 7,202 × 100 ft, asphalt - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 53; injuries: fatal; private; airplane ratings: single-engine land; medical: class 3, with waivers/limitations; last flight review May 15, 2022; seat: left; restraint: lap only; toxicology performed; flight hours: 131.9 total, 14.2 in the last 30 days, 2.5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 360° at 7 knots, gusting 17 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 77 °F, dew point 14 °F - Altimeter: 30.13 inHg - Observed at: KSOW, 1 nm away - METAR: 5:57 PM 75 °F 18 °F 12 % E 13 mph 0 mph 23.25 in 0.0 in Fair ## 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 20220525008739A](https://openairdocs.org/incident/20220525008739A), May 25, 2022: Cessna 172F, Show Low, AZ, Destroyed, 2 fatal. Aircraft departed runway 25 and was having trouble gaining altatude and impacted the ground about 1 mile from the end of runway 25 ## Docket (11 files) The files NTSB released with the investigation on November 8, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=105133. 20.5 MB in all. - Materials laboratory factual report (item 1, PDF, 16 pages, 20 photos, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14817925&FileExtension=pdf&FileName=22-090%20-%20Materials%20Lab%20Factual%20Report%20(WPR22FA188)-Rel.pdf - Witness statements (item 2, PDF, 4 pages, 296 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16102674&FileExtension=pdf&FileName=Witness%20Binder-Rel.pdf - Record of conversation - supervisor (item 3, PDF, 1 page, 116 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14905270&FileExtension=pdf&FileName=Record%20of%20Conversation%20-%20Pettit-Rel.pdf - Textron technical report (item 4, PDF, 10 pages, 4 photos, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14911351&FileExtension=pdf&FileName=Textron%20Tech%20Report%2017253113-Rel.pdf - No. 4 cylinder examination notes (item 5, PDF, 3 pages, 3 photos, 542 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14904807&FileExtension=pdf&FileName=Memorandum%20of%20Record%20-%20No.%204%20Cylinder%20Examination-Rel.pdf - Maintenance records (item 6, PDF, 32 pages, 10.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14007637&FileExtension=pdf&FileName=Airframe%20Logbooks_Redacted-Rel.pdf - No. 2 cylinder work order (item 7, PDF, 3 pages, 3.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14905853&FileExtension=pdf&FileName=No%202%20Cylinder%20Work%20Order%20-%20Poplar%20Grove_Redacted-Rel.pdf - Airworthiness certificate (item 8, PDF, 1 page, 379 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15117996&FileExtension=pdf&FileName=5532R-Airworthiness_Redacted-Rel.pdf - Airplane registration (item 9, PDF, 7 pages, 186 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16103776&FileExtension=pdf&FileName=5532R-Registration-Rel.pdf - Statement of party representatives to NTSB investigation (item 10, PDF, 9 pages, 365 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14905863&FileExtension=pdf&FileName=Party%20Form%20-%20Textron%20Signed_Redacted-Rel.pdf - Evidence control form (item 11, PDF, 2 pages, 29 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15363818&FileExtension=pdf&FileName=Evidence-Control-Form%20No%204%20Cyl_Redacted-Rel.pdf 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.