# NTSB WPR21LA020: Piper PA-28-180, N7405W, Show Low, AZ, October 21, 2020 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: October 21, 2020, 11:17 local (18:17 UTC) - Place: Show Low, AZ · Highway - Coordinates: 34.265472, -110.00566 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.2655&lon=-110.0057&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA - NTSB case key (mKey): 102177 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA020 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102177/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102177 - Page: https://openairdocs.org/ntsb/WPR21LA020 ## Probable cause A partial loss of engine power due to the failure of the No. 4 cylinder exhaust valve. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Piper PA-28-180, 3 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=7102808), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Piper PA-28-180, 19 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=7102808), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Enroute-cruise: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Piper PA-28-180, 40 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=7102808), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot reported that, while in cruise flight about 8,000 ft mean sea level, there was a loud bang followed by severe engine vibration and the engine lost partial power. The pilot attempted to troubleshoot; however, the engine continued to produce less than full power. The pilot declared an emergency and performed a forced landing to a highway, during which the airplane’s right wing impacted a barbed wire fence, resulting in substantial damage. Examination of the engine revealed a stuck exhaust valve on the No. 4 cylinder. The exhaust valve head had separated from the valve stem. The loose valve head was found in the cylinder’s combustion chamber; the combustion chamber and piston dome exhibited damage consistent with repeated contact with the valve head. The loss of engine power is consistent with the failure of the No. 4 cylinder exhaust valve; however, the reason for the valve failure could not be determined based on the available information. ## Factual narrative On October 21, 2020, about 1117 mountain standard time, a Piper PA-28-180 airplane, N7405W, was substantially damaged when it was involved in an accident near Show Low, Arizona. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations (CFR) Part 91 personal flight. The pilot reported that, while in cruise flight about 8,000 ft mean sea level, there was a loud bang followed by severe engine vibration and the engine lost partial power. The pilot attempted to troubleshoot; however, the engine continued to produce about 1,600 to 1,700 rpm. The pilot declared an emergency and performed a forced landing to a highway, during which the airplane’s right wing impacted a barbed wire fence. Examination of the engine revealed a stuck exhaust valve on the No. 4 cylinder. The exhaust valve head had separated from the valve stem. The loose valve head was found in the cylinder’s combustion chamber; the combustion chamber and piston dome exhibited damage consistent with repeated contact with the valve head. ## Aircraft - Registration: [N7405W](https://openairdocs.org/aircraft/N7405W), registered now, S/N 28-1291, built 1963 (OpenAirDocs) - Reported make and model: PIPER PA-28-180 - Registry model: [Piper PA-28-180](https://openairdocs.org/model/piper-pa-28-180) (registry code 7102808) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 28-1291 - Airframe hours: 4551.8 - Engines: Lycoming O-360 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Avra Valley Flyers LLC - Airworthiness certificate: Standard, Normal - Last inspection: Annual, May 27, 2020 - Departed: KAVQ, Marana, AZ - Flight plan: VFR - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; injuries: none; commercial; airplane ratings: single-engine land; instrument ratings: airplane, helicopter; medical: class 3, without waivers/limitations; last flight review September 17, 2020; seat: left; flight hours: 1,885 total, 15 in this make and model, 1,100 as pilot in command, 36 in the last 90 days, 25 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 240° at 10 knots, gusting 15 - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 14 °F - Altimeter: 30.16 inHg - Observed at: KSOW ## 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 20201021019669A](https://openairdocs.org/incident/20201021019669A), Oct 21, 2020: Piper PA-28-180, Show Low, AZ, Substantial damage. On 10/21/2020, at 1117 PDT, N7405H, pa 28-180, emergency landing on hwy 60 due to loss of engine power. Aircraft sustained substantial damage to the right wing… ## Docket (3 files) The files NTSB released with the investigation on November 8, 2022, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102177. 2.7 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14596413&FileExtension=pdf&FileName=NTSB%206120%20Final_Redacted-Rel.pdf - Airframe and engine examination summary report (item 2, PDF, 4 pages, 334 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14702663&FileExtension=pdf&FileName=WPR20LA020%20Engine%20Examination%202-Rel.pdf - Logbook excerpt (item 3, PDF, 1 page, 171 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14607125&FileExtension=pdf&FileName=Annual%20Inspection_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.