# NTSB ERA16LA041: Woodrow Larry W Sonex, N7035Z, Morganton, NC, November 15, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: November 15, 2015, 14:45 local (19:45 UTC) - Place: Morganton, NC - Coordinates: 35.820278, -81.611389 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.8203&lon=-81.6114&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report February 17, 2016 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 92327 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA16LA041 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/92327/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=92327 - Page: https://openairdocs.org/ntsb/ERA16LA041 ## Probable cause The pilot/owner’s inadequate maintenance inspection following a propeller strike, which resulted in the subsequent in-flight propeller separation due to propagation of fatigue cracks in the crankshaft. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng front section](https://openairdocs.org/ntsb-findings/01058510): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Woodrow Larry W SONEX, 1 case](https://openairdocs.org/ntsb-findings/01058510/cases.md?model=05617QL), [All aircraft, 13 cases](https://openairdocs.org/ntsb-findings/01058510/cases.md) - [Inspection: scheduled/routine inspection](https://openairdocs.org/ntsb-findings/02061520): Personnel issues › Task performance · Owner/builder (probable cause); cases with it: [Woodrow Larry W SONEX, 1 case](https://openairdocs.org/ntsb-findings/02061520/cases.md?model=05617QL), [All aircraft, 167 cases](https://openairdocs.org/ntsb-findings/02061520/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Woodrow Larry W SONEX, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=05617QL), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Woodrow Larry W SONEX, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05617QL), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Woodrow Larry W SONEX, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05617QL), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Woodrow Larry W SONEX, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05617QL), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The private pilot, who was also the owner/builder of the experimental, amateur-built airplane, reported that, during initial climb for the local flight, about 3,000 ft mean sea level, the propeller separated from the airplane and fell to the ground. The pilot/owner turned the airplane toward an airport that had a longer runway than the departure airport and attempted to glide the airplane to the runway. However, the airplane did not have sufficient altitude, and it subsequently impacted trees about 600 ft short of the runway. Photographs of the crankshaft revealed that it fractured just aft of the propeller mounting hub/flange. The fracture surfaces on the hub exhibited features consistent with fatigue crack propagation through the wall thickness of the crankshaft and the subsequent overstress fracture of the remaining portion of the crankshaft. Review of maintenance records revealed that the airplane had sustained a propeller strike about 7 years before the accident. After that event, the pilot/owner, who performed his own maintenance, replaced the propeller; however, he did not disassemble the engine or otherwise document any inspection or replacement of the crankshaft in the airplane's maintenance records. ## Factual narrative On November 15, 2015, about 1445 eastern standard time, an experimental, amateur-built Sonex, N7035Z, operated by a private individual, was substantially damaged during a forced landing into trees, while on approach to Foothills Regional Airport (MRN), Morganton, North Carolina. The private pilot and passenger were not injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the local flight that departed Lower Creek Airport (NC27), Lenoir, North Carolina, about 1440. The pilot reported that during initial climb from NC27, about 3,000 feet mean sea level, the propeller separated from the airplane and fell to the ground. The pilot turned the airplane toward MRN and attempted to glide to runway 21, but did not have sufficient altitude to glide to the runway and impacted trees about 600 feet short of the runway. The pilot owned the airplane and performed the maintenance on it himself. He completed construction of the airplane in 2005 and it was issued a Federal Aviation Administration (FAA) experimental airworthiness certificate. The airplane was equipped with an Aerovee 80-horsepower engine. At the time of the accident, the airframe and engine had accumulated 278.5 hours since new and the airplane's most recent annual condition inspection was completed on April 14, 2015. Examination of the airplane by an FAA inspector revealed that it came to rest nose-down in trees about 600 feet prior to the approach end of runway 21. During the impact, both wings and the fuselage sustained damage. The inspector added that review of the maintenance records revealed that the airplane had experienced a propeller strike on August 28, 2006, at 21.9 total hours since new. Following the propeller strike, the pilot replaced the propeller, but did not inspect the engine crankshaft. Additionally, the crankshaft was not required to be inspected, through such means as ultrasonic or magnetic particle inspection, on an experimental airplane. NTSB metallurgical examination of photographic evidence revealed that the crankshaft fractured just aft of the propeller mounting hub/flange, allowing the propeller assembly to separate from the airplane. Examination of images of the fracture surfaces on the hub attached to the propeller revealed fracture surface features consistent with fatigue crack propagation through the wall thickness of the crankshaft and subsequent overstress fracture of the remaining portion of crankshaft. According to a representative of the engine manufacturer, they did not publish guidance regarding the maintenance actions necessary following a propeller strike. When contacted by customers following such events, they routinely recommend some form of inspection relative to the severity of the event. For minor cases, a measurement of crankshaft run-out was recommended, with procedures regarding how to conduct the measurement published ina service bulletin. For more serious cases, the manufacturer typically recommended an engine disassembly, magnaflux inspection, and possibly a precautionary replacement of the crankshaft. The engine manufacturer could not locate any records documenting contact with the accident owner/pilot following the airplane's 2006 propeller strike. According to FAA Advisory Circular 43.13-1B - Acceptable Methods, Techniques, and Practices - Aircraft Inspection and Repair, "Every engine that suffers a sudden stoppage must be inspected in accordance with the manufacturer's maintenance instructions before being returned to service. If the engine manufacturer does not provide the required information, then the engine case must be opened and every major component part must be inspected using visual and/or nondestructive inspection procedures as applicable." ## Aircraft - Registration: [N7035Z](https://openairdocs.org/deregistered/N7035Z-2016-12-13), registration cancelled 2016-12-13, S/N 605, built 2005 (OpenAirDocs) - Reported make and model: WOODROW LARRY W SONEX (NO SERIES) - Registry model: [Woodrow Larry W SONEX](https://openairdocs.org/model/woodrow-larry-w-sonex) (registry code 05617QL) (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: 605 - Year built: 2005 - Airframe hours: 279 - Engines: Larry Woodrow Aerovee2002 80 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Woodrow Larry W - Registered owner: Woodrow Larry W - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 15, 2015, 17 hours before - Departed: NC27, Lenoir, NC - Destination: NC27, Lenoir, NC - Airport: MRN, Foothills Regional Airport, runway 21, 5,500 × 75 ft, asphalt - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 78; injuries: none; private; airplane ratings: single-engine land; medical: sport pilot; last flight review June 25, 2014; seat: left; restraint: 4-point; flight hours: 339 total, 269 in this make and model, 279 as pilot in command, 7 in the last 90 days, 2 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 63 °F, dew point 55 °F - Altimeter: 30.40 inHg - Observed at: MRN, 1 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 20151115023369A](https://openairdocs.org/incident/20151115023369A), Nov 15, 2015: Woodrow Larry W SONEX, Morganton, NC, Destroyed. On 11/15/2015 at 1435 hours EDT, N7035Z, a Sonex experimental aircraft, departed lower creek airport (NC27) with the pilot and one passenger on board. At about… ## Docket (6 files) The files NTSB released with the investigation on January 11, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=92327. 1.5 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 393 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435465&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - NTSB Materials Laboratory Factual Report (item 2, .PDF, 1 photo, 272 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435464&FileExtension=.PDF&FileName=NTSB%20Materials%20Laboratory%20Factual%20Report-Master.PDF - FAA Inspector Statement (item 3, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435466&FileExtension=.PDF&FileName=FAA%20Inspector%20Statement-Master.PDF - Excerpt from Maintenance Records (item 4, .PDF, 114 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435467&FileExtension=.PDF&FileName=Excerpt%20from%20Maintenance%20Records-Master.PDF - Correspondence from Engine Manufacturer (item 5, .PDF, 38 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435468&FileExtension=.PDF&FileName=Correspondence%20from%20Engine%20Manufacturer-Master.PDF - Photos (Courtesy of FAA) (item 6, .PDF, 2 photos, 650 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40435469&FileExtension=.PDF&FileName=Photos%20(Courtesy%20of%20FAA)-Master.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.