# NTSB WPR19LA114: Great Lakes 2T-1A-2, N101GL, San Diego, CA, March 15, 2019 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: March 14, 2019, 17:30 local (Mar 15, 2019, 00:30 UTC) - Place: San Diego, CA - Coordinates: 32.815555, -117.13972 - Nearby events: https://openairdocs.org/map.md?lat=32.8156&lon=-117.1397&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-climb to cruise: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 99276 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR19LA114 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/99276/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=99276 - Page: https://openairdocs.org/ntsb/WPR19LA114 ## Probable cause The fracture of the aileron hinge strap due to fatigue crack propagation, which resulted in substantial damage to a wing rib aft of the spar at the outboard aileron cutout. Contributing to the accident was inadequate maintenance inspection. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Flight control system: aileron control system](https://openairdocs.org/ntsb-findings/01022710): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Great Lakes 2T-1A-2, 1 case](https://openairdocs.org/ntsb-findings/01022710/cases.md?model=3910101), [All aircraft, 45 cases](https://openairdocs.org/ntsb-findings/01022710/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [Great Lakes 2T-1A-2, 2 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=3910101), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-climb to cruise: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333) (defining event); cases with it: [Great Lakes 2T-1A-2, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=3910101), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) - [Emergency descent: Flight control sys malf/fail](https://openairdocs.org/ntsb-events/333); cases with it: [Great Lakes 2T-1A-2, 1 case](https://openairdocs.org/ntsb-events/333/sequence.md?model=3910101), [All aircraft, 410 cases](https://openairdocs.org/ntsb-events/333/sequence.md) ## Analysis About 5 minutes after taking off, the pilot observed that the left upper aileron had come loose from the inboard hinge. The pilot returned to the departure airport and landed uneventfully. A postaccident examination of the airplane revealed that a wing rib aft of the spar at the outboard aileron cutout was substantially damaged. Examination of the aileron hinge strap fracture surfaces revealed crack arrest marks and thumbnail-shaped patterns on the fracture surfaces, which emanated from both the top and bottom surfaces of the hinge strap. The fracture surfaces were consistent with asymmetric reverse-bending fatigue crack propagation. The fatigue cracking propagated from the top and bottom surfaces through almost the entire cross-section of the hinge strap. The pilot reported that while there were no inspection criteria from the manufacturer relative to the hinge straps, all hinge straps were inspected as part of each annual inspection. ## Factual narrative On March 14, 2019, about 1730 Pacific daylight time, a Great Lakes 2T-1A-2 airplane, N101GL, sustained substantial damage when it was involved in an accident near San Diego, California. The private pilot and his passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. In a report submitted to the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), the pilot reported that, about 5 minutes after takeoff, the left upper aileron came loose from the inboard hinge and remained attached by the one remaining hinge. The pilot returned to the departure airport and landed uneventfully. Examination of the airplane revealed that a wing rib aft of the spar at the outboard aileron cutout was substantially damaged. The failed aileron hinge strap (two components) was secured by the NTSB IIC and sent to the NTSB Materials Laboratory for examination. The pilot mentioned that while there were no inspection criteria from the manufacturer relative to the hinge straps, all hinge straps were inspected as part of each annual inspection. Examination of the aileron hinge strap fracture surfaces by the NTSB Materials Laboratory technician revealed crack arrest marks and thumbnail-shaped patterns on the fracture surfaces emanating from both the top and bottom surfaces of the hinge strap. The thumbnail-shaped patterns are ratchet marks and their presence on both the top and bottom surfaces is consistent with asymmetric reverse-bending fatigue crack propagation. The fatigue cracking propagated from the top and bottom surfaces through almost the entire cross-section of the hinge strap. ## Aircraft - Registration: [N101GL](https://openairdocs.org/aircraft/N101GL), registered now, S/N 0714 (OpenAirDocs) - Reported make and model: Great Lakes 2T-1A-2 - Registry model: [Great Lakes 2T-1A-2](https://openairdocs.org/model/great-lakes-2t-1a-2) (registry code 3910101) (OpenAirDocs) - Registry engine: [Lycoming I0360 series](https://openairdocs.org/engine/lycoming-i0360-series) (registry code 41515, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 0714 - Year built: 1975 - Airframe hours: 2412 - Engines: Lycoming AEIO-360-B1G6 180 hp reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Aerobatic; Standard, Normal - Last inspection: Annual, August 30, 2018, 10 hours before - Departed: MYF, San Diego, CA - Airport: MYF, Montgomery-Gibbs Executive, runway 28R, 4,598 × 150 ft, asphalt - Equipment: Unknown ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; seat: rear; restraint: 4-point; flight hours: 1,146 total, 155 in this make and model, 960 as pilot in command, 28 in the last 90 days, 8 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 280° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 64 °F, dew point 43 °F - Altimeter: 29.92 inHg - Turbulence: Light - Observed at: MYF ## 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 20190314001459A](https://openairdocs.org/incident/20190314001459A), Mar 14, 2019: Great Lakes 2T-1A-2, San Diego, CA, Minor damage. This is a biplane type aircraft. The ailerons are held in place by metal straps. There are two straps for each top aileron. Ten minutes into the flight the… ## Other investigations on N101GL (2) 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 FTW82DPA06](https://openairdocs.org/ntsb/FTW82DPA06), Nov 18, 1981: Great Lakes 2T-TA (N101GL), Waco, TX, substantial damage - [NTSB FTW77DPG04](https://openairdocs.org/ntsb/FTW77DPG04), Oct 26, 1976: Great Lakes 2T-1A (N101GL), Van Buren, AR, substantial damage ## Docket (6 files) The files NTSB released with the investigation on November 2, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=99276. 19.7 MB in all. - Materials laboratory factual report (item 1, PDF, 5 pages, 624 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12370481&FileExtension=pdf&FileName=Materials%20Laboratory%20Factual%20Report%2019-050-Rel.pdf - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 2, PDF, 9 pages, 2.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12370657&FileExtension=pdf&FileName=Pilot%20accident%20report%20form_redacted-Rel.pdf - Record of conversation - aileron hinge strap inspection criteria (item 3, PDF, 1 page, 122 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12435431&FileExtension=pdf&FileName=Record%20of%20Conversation%20with%20pilot-owner%20%20%20aileron%20hinge%20strap%20inspection%20criteria-Rel.pdf - Receipt for return of part (item 4, PDF, 2 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12370781&FileExtension=pdf&FileName=WPR19LA114%20-%20Receipt%20of%20Returned%20Part_Redacted-Rel.pdf - Evidence control form (item 5, PDF, 1 page, 14.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12370491&FileExtension=pdf&FileName=Evidence%20Control%20Form%20WPR19LA114-2019-001%20-%20steet%20airleron%20hinge%20strap_Redacted-Rel.pdf - Photo array of failed aileron hinge strap (item 6, PDF, 4 pages, 562 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12431498&FileExtension=pdf&FileName=Photo%20array%20of%20failed%20aileron%20hinge%20strap-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.