# NTSB WPR23LA317: Piper PA-24-260, N503JA, Fullerton, CA, August 8, 2023 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: August 8, 2023, 15:00 local (22:00 UTC) - Place: Fullerton, CA - Coordinates: 33.872014, -117.97978 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.8720&lon=-117.9798&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration FSDO - NTSB case key (mKey): 192891 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR23LA317 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/192891/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=192891 - Page: https://openairdocs.org/ntsb/WPR23LA317 ## Probable cause The separation of the stabilator actuator from the stabilator tab, which resulted in pitch control surface flutter and structural damage. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Flight control system: elevator tab control system](https://openairdocs.org/ntsb-findings/01022731): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Piper PA-24-260, 1 case](https://openairdocs.org/ntsb-findings/01022731/cases.md?model=7102406), [All aircraft, 37 cases](https://openairdocs.org/ntsb-findings/01022731/cases.md) - [Flight control system: elevator tab control system](https://openairdocs.org/ntsb-findings/01022731): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Piper PA-24-260, 1 case](https://openairdocs.org/ntsb-findings/01022731/cases.md?model=7102406), [All aircraft, 37 cases](https://openairdocs.org/ntsb-findings/01022731/cases.md) - [Flight control system: elevator tab control system](https://openairdocs.org/ntsb-findings/01022731): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Piper PA-24-260, 1 case](https://openairdocs.org/ntsb-findings/01022731/cases.md?model=7102406), [All aircraft, 37 cases](https://openairdocs.org/ntsb-findings/01022731/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) (defining event); cases with it: [Piper PA-24-260, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=7102406), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) - [Enroute-cruise: Aircraft structural failure](https://openairdocs.org/ntsb-events/337); cases with it: [Piper PA-24-260, 3 cases](https://openairdocs.org/ntsb-events/337/sequence.md?model=7102406), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) ## Analysis Shortly after takeoff the airplane began to shake violently with the control yoke moving rapidly forward and aft from stop to stop. The pilot was able to perform an on-airport emergency landing after shutting down the engine, but sustained hand injuries due to the extreme control forces and oscillations. The airplane sustained substantial damage to the stabilator structure in a manner consistent with it exhibiting aerodynamic flutter. Postaccident examination revealed that the stabilator tab actuator was disconnected from the control tab, and the bolt, nut, and washer that connected them were missing. The disconnection of the actuator allowed the tab surface to uncouple, which resulted in flutter and structural damage to the stabilator. Circumferential scoring around the bolt hole within the tabs indicated that the bolt was likely loose for an undetermined period before failure. The nut had likely not been replaced since the airplane was manufactured almost 60 years before the accident, so its locking properties would have been significantly diminished. ## Factual narrative On August 8, 2023, about 1500 Pacific daylight time, a Piper PA-24-260, N503JA, was substantially damaged when it was involved in an accident near Fullerton, California. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that, shortly after takeoff, the airplane began to shake violently with the control yoke moving rapidly forward and aft from stop to stop. The vibrations were so extreme that he assumed the engine had suffered a catastrophic failure, such as a detached engine cylinder. He shut down the engine and turned the airplane back to the airport for landing. The pilot stated he was able to land, but sustained hand injuries due to the extreme control forces and oscillations. The airplane sustained substantial damage to the stabilator structure and postaccident examination revealed that the stabilator tab actuator was disconnected from the control tab, and the bolt, nut, and washer that connected them were missing (figure 1). Figure 1 - Stabilator tab disconnected from the actuator. The tabs sustained extensive scratch and peening damage to both their inner and forward surfaces consistent with high frequency oscillations. The paint around the end of the tab actuator arm had chipped away, revealing similar peening damage to its steel surface. Neither the bolt nor the nut that connected the tabs to the actuator were located, and there was circumferential scoring to the tabs around the bolt hole bore. Neither bolt hole appeared to be elongated. Likewise, the bushing within the actuator did not appear to be out of round. According to the airplane’s illustrated parts catalog, the actuator retaining nut was supposed to be a self-locking type, with no provisions for a cotter pin. The mechanic who had performed an annual inspection 5.5 flight hours before the accident stated that he did not remove or replace either the bolt or the nut, and that he performed a functional check of the pitch trim system with no anomalies noted. Examination of the maintenance logbooks did not reveal any evidence that the nut had been replaced since the airplane was manufactured in 1965. ## Aircraft - Registration: [N503JA](https://openairdocs.org/aircraft/N503JA), registered now, S/N 24-4165, built 1965 (OpenAirDocs) - Reported make and model: PIPER PA-24-260 - Registry model: [Piper PA-24-260](https://openairdocs.org/model/piper-pa-24-260) (registry code 7102406) (OpenAirDocs) - Registry engine: [Lycoming TI0-540 series](https://openairdocs.org/engine/lycoming-ti0-540-series) (registry code 41533, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: 24-4165 - Year built: 1965 - Airframe hours: 3849.7 - Engines: Lycoming IO-540-D4A5 260 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 1, 2023, 5.5 hours before - Departed: FUL, Fullerton, CA - Destination: POC, La Verne, CA - Airport: FUL, Fullerton Muni, runway 24, 3,121 × 75 ft, asphalt - Equipment: Data recorder, ADS-B, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: minor; flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review April 14, 2022; seat: left; restraint: 3-point; flight hours: 2,441.6 total, 125 in this make and model, 2,351.8 as pilot in command, 190 in the last 90 days, 40 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 190° at 7 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 84 °F, dew point 63 °F - Altimeter: 29.96 inHg - Observed at: KFUL - METAR: METAR KFUL 082253Z 19007KT 10SM CLR 29/17 A2996 RMK AO2 SLP145 T02890167= ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 20230808015419I](https://openairdocs.org/incident/20230808015419I), Aug 8, 2023: Piper COMANCHE, Fullerton, CA, Minor damage. 08/08/2023- Aircraft depart ful R24, departed right downwind. Upon leveling off at 2500 heading east pilot reported "yoke started to jackhammer back and forth… ## Docket (4 files) The files NTSB released with the investigation on June 20, 2024, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=192891. 8.7 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 7 pages, 7.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16312898&FileExtension=pdf&FileName=r_6120_Redacted-Rel.pdf - NTSB factual examination report (item 2, PDF, 7 pages, 7 photos, 948 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16315766&FileExtension=pdf&FileName=Exam%20Report-WPR23LA317-Rel.pdf - Maintenance logbook excerpts (item 3, PDF, 2 pages, 273 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16313583&FileExtension=pdf&FileName=r_Logbook%20Excerpts_Redacted-Rel.pdf - Stabilator trim parts catalog excerpts (item 4, PDF, 4 pages, 181 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=16313947&FileExtension=pdf&FileName=IPC%20Stab%20Trim-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.