# NTSB WPR22LA035: Sonex Waiex B, N535D, Laveen Village, AZ, November 15, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: November 15, 2021, 11:30 local (18:30 UTC) - Place: Laveen Village, AZ - Coordinates: 33.349191, -112.12963 - Nearby events: https://openairdocs.org/map.md?lat=33.3492&lon=-112.1296&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA-FSDO - NTSB case key (mKey): 104244 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR22LA035 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/104244/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=104244 - Page: https://openairdocs.org/ntsb/WPR22LA035 ## Probable cause Failure of the rocker swivel assembly due to either wear or corrosion, which resulted in a loss of engine power. ## 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 · Failure (probable cause); cases with it: [Lou Pappas WAIEX B, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=05637HX), [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: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Lou Pappas WAIEX B, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05637HX), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Landing: Ground collision](https://openairdocs.org/ntsb-events/200); cases with it: [Lou Pappas WAIEX B, 1 case](https://openairdocs.org/ntsb-events/200/sequence.md?model=05637HX), [All aircraft, 618 cases](https://openairdocs.org/ntsb-events/200/sequence.md) ## Analysis The pilot reported the engine began running rough during cruise flight, and the airplane could not maintain altitude. The pilot initiated a forced landing to an airstrip and during the descent realized that he was not going to make the airstrip, so he elected to landed on the desert terrain. The airplane impacted rocks and a barbed wire fence which caused the airplane to nose over, which resulted in substantial damage to the wings, stabilizers, and ruddervators. Postaccident examination of the engine revealed that the No. 4 exhaust rocker assembly swivel housing separated from the screw body, likely due to wear of the swivel and the swivel pad housing. This wear likely occurred because of either incorrect spacing between the pad and valve, or corrosion. ## Factual narrative On November 15, 2021, about 1130 mountain standard time, an experimental amateur-built Sonex Waiex-B airplane, N535D, was substantially damaged when it was involved in an accident near Laveen Village, Arizona. The pilot was not injured. The airplane was operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had been flying for about 48 minutes when the engine began to run rough. He said the airplane did not have enough power to maintain altitude and he initiated a forced landing to an airstrip. The pilot realized he was not going to make the airstrip and landed on desert terrain, impacting rocks and a barbed wire fence which caused the airplane to nose over which resulted in substantial damage to the wings, stabilizers, and ruddervators. The pilot was able to exit the cabin area through the broken canopy. Examination of the airplane revealed that the No. 4 cylinder exhaust valve rocker arm swivel housing and swivel pad separated from its screw body. The screw body remained secured to the rocker arm. The swivel pad and swivel housing were found loose in the rocker cover. The swivel pad remained loose in the swivel housing and impact damage was visible on the swivel housing fracture surface. The rocker assembly for No. 3 and 4 cylinders and the separated swivel housing and swivel pad (see figure) were sent to the National Transportation Safety Board Materials Laboratory for forensic examination. The examination revealed a damaged fracture surface of the swivel housing and the screw body. The spherical outboard side of the swivel pad had a rough surface consistent with scoring and galling damage. The damage pattern had circular patterns on two sides with linear features in between, consistent with rotating contact within the swivel housing. The swivel housing had scoring and galling that mirrored the damage patterns observed on the swivel pad with a circular pattern on two sides and linear scratches between. The interior of the swivel housing had worn away, producing a space for the swivel pad to be recessed within the housing. This worn area was located near the facture surface of the swivel housing and screw body. Figure - Overall view of the rocker assembly showing the inboard side of the rocker arms including the fractured No. 4 exhaust valve adjuster. Review of the airplane’s maintenance records revealed that the engine was assembled on May 9, 2018. The last inspection was completed on October 12, 2021, with about 110 hours of engine operation since the engine had been assembled. At this time, the cylinders were torqued, and the valves were adjusted. The airplane flew another 25 hours before the accident. ## Aircraft - Registration: [N535D](https://openairdocs.org/deregistered/N535D-2023-05-04), registration cancelled 2023-05-04, S/N WXB0010, built 2018 (OpenAirDocs) - Reported make and model: Sonex WAIEX B - Registry model: [Lou Pappas WAIEX B](https://openairdocs.org/model/lou-pappas-waiex-b) (registry code 05637HX) (OpenAirDocs) - Registry engine: [Amateur-built UNKNOWN ENG](https://openairdocs.org/engine/amateur-built-unknown-eng) (registry code 99999) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: WXB0010 - Year built: 2018 - Airframe hours: 145 - Engines: Aerovee Turbo 100 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Air-Spaces LLC - Registered owner: Air-Spaces LLC - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 10, 2021, 20 hours before - Departed: GEU, Glendale, AZ - Airport: AZ90, Hangar Haciendas, runway 08/26, 2,436 × 24 ft, asphalt - Equipment: Auto-pilot, Angle of attack indicator, ADS-B, Stall warning system, Onboard weather, Electronic multifunction display, Electronic flight bag or handheld device, Data recorder ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 69; injuries: minor; private; airplane ratings: single-engine land; medical: basicmed, unknown; last flight review January 28, 2021; seat: left; restraint: 4-point; flight hours: 2,400 total, 550 in this make and model, 2,300 as pilot in command, 30 in the last 90 days, 15 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 10 statute miles - Lowest ceiling: none - Icing: Unknown - Turbulence: Unknown - Observed at: GEU, 14 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 20211115020069A](https://openairdocs.org/incident/20211115020069A), Nov 15, 2021: Lou Pappas WAIEX B, Laveen, AZ, Substantial damage. Pilot departed geu and had been flying for approximately 45 minutes. During his return flight from cgz to geu, at an altitude of 3500FT, the engine began… ## Docket (4 files) The files NTSB released with the investigation on August 15, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=104244. 5.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15555571&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - NTSB airframe and engine examination summary (item 2, PDF, 7 pages, 6 photos, 742 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15584076&FileExtension=pdf&FileName=WPR22LA035%20Airframe%20and%20Engine%20Examination%20Summary-Rel.pdf - Materials laboratory factual report 22-062 (item 3, PDF, 10 pages, 12 photos, 2.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=14400801&FileExtension=pdf&FileName=22-062-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 4, PDF, 1 page, 370 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15583893&FileExtension=pdf&FileName=wreckage%20release%20form-signed._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.