# NTSB ERA13LA197: Piper PA-28-181, N3060B, Winston Salem, NC, April 7, 2013 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 7, 2013, 15:40 local (19:40 UTC) - Place: Winston Salem, NC - Coordinates: 36.134998, -80.219718 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.1350&lon=-80.2197&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report August 29, 2013 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 86630 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA13LA197 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/86630/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=86630 - Page: https://openairdocs.org/ntsb/ERA13LA197 ## Probable cause Fatigue failure of the right main landing gear attach bolts due to an unreported hard landing at an unknown time, and subsequent collapse of the landing gear. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: main landing gear attach sec](https://openairdocs.org/ntsb-findings/01023211): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Piper PA-28-181, 1 case](https://openairdocs.org/ntsb-findings/01023211/cases.md?model=7102807), [All aircraft, 66 cases](https://openairdocs.org/ntsb-findings/01023211/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Prior to flight: Aircraft maintenance event](https://openairdocs.org/ntsb-events/040); cases with it: [Piper PA-28-181, 2 cases](https://openairdocs.org/ntsb-events/040/sequence.md?model=7102807), [All aircraft, 484 cases](https://openairdocs.org/ntsb-events/040/sequence.md) - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Piper PA-28-181, 11 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=7102807), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis While landing in gusty wind conditions, the fixed right main landing gear collapsed during rollout. Metallurgical examination of the right main landing gear trunion revealed extensive wear, fretting, hole elongation, and disturbed metal around the holes of the lower trunion flange. Additionally, two bolt heads were recovered from the lower flange holes and exhibited fatigue at their respective fracture surfaces. The bolt fatigue, in conjunction with the excessive wear and damage at the lower flange, was consistent with bolt looseness and wear over a period of time. According to the airplane manufacturer, similar events involved airplanes used for student pilot training, such as the accident airplane, which experienced a previous hard landing that went unreported. The damage could then propagate over time, but it was difficult to tell if the initiating hard landing occurred months or years before the actual landing gear failure. However, mechanics commonly check the bolts during annual and 100-hour inspections. Specifically, they check the condition and security by verifying the proper exposed thread count and that the cotter pins were in place. The accident airplane's most recent annual inspection was completed about 3 months before the accident and the airplane had flown about 51 hours since that inspection. The two mechanics who performed the most recent annual inspection reported that the bolts were visually inspected and attempts were made to check retention and security of the hardware with tools; however, the nuts were in an area that was difficult to access with tools. It could not be determined if the wear began before or after the most recent annual inspection. ## Factual narrative On April 7, 2013, about 1540 eastern daylight time, a Piper PA-28-181, N3060B, operated by Piedmont Flight Training, was substantially damaged when the right main landing gear collapsed during rollout at Smith Reynolds Airport (INT), Winston Salem, North Carolina. The private pilot and flight instructor were not injured. The instructional 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 flight that departed Asheville Regional Airport (AVL), Asheville, North Carolina, about 1430. The private pilot reported that after an uneventful cross-country flight, the airplane was landing on runway 22 at INT. The touchdown was normal; however, the right main landing gear collapsed during rollout and the airplane came to rest on the runway. The operator reported that during the accident landing, the airplane left approximately 850 feet of skid marks on the runway from the right main landing gear tire, with no corresponding skid marks from the left main landing gear tire. An additional 435 feet of scrape marks continued beyond the 850-foot skid marks, consistent with the collapse of the right main landing gear. Examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed substantial damage to the right wing. The right main landing gear trunion was forwarded to the NTSB Materials Laboratory, Washington, DC, for further examination. The trunion attached to the wing via four bolts through an upper flange and four bolts through a lower flange. Metallurgical examination revealed extensive wear, fretting, hole elongation, and disturbed metal around the holes of the lower flange. The wear was more pronounced at the two most outboard holes of the lower flange. Additionally, two bolt heads were recovered and exhibited white paint, consistent with their preimpact location being from the lower flange. The fracture surfaces of both bolt heads exhibited fatigue. The bolt fatigue in conjunction with the excessive wear and damage at the lower flange attachment bolt holes was consistent with bolt looseness and wear over a period of time. Review of NTSB Materials Laboratory records did not reveal any similar events within the past 10 years. According to a representative from the airplane manufacturer, he had seen similar events in the past and such wear usually involved airplanes used for student pilot training. The airplanes would suffer an initiating hard landing that was not reported by the student pilot. The damage could then propagate over time, but it was difficult to tell if the initiating hard landing occurred months or years prior to the actual landing gear failure; however, it was also common practice for mechanics to check the bolts during annual and 100-hour inspections. Specifically, they usually checked for condition and security by verifying the proper exposed thread count and that the cotter pins were in place. Reviewof the make and model airplane maintenance manual for 100-hour inspections revealed, "16. Inspect gear struts and mounting bolts for condition and security." The airplane's most recent annual inspection was completed on January 11, 2013. At that time, the airplane had accrued 6,762 total hours of operation. The airplane accumulated an additional 51 hours of operation, from the time of the most recent annual inspection, until the accident. According to an FAA inspector, the operator did not employ mechanics, but rather contracted mechanics when maintenance was required. During interviews, the two mechanics that performed the most recent annual inspection stated that the bolts were visually inspected and attempts were made to check retention and security of the hardware with tools; however, the nuts were in an area that was difficult to access with tools. The recorded wind at INT, at 1554, was from 200 degrees at 10 knots, gusting to 17 knots, and varying between 150 degrees and 230 degrees. ## Aircraft - Registration: [N3060B](https://openairdocs.org/aircraft/N3060B), registered now, S/N 28-7990139, built 1978 (OpenAirDocs) - Reported make and model: PIPER PA-28-181 - Registry model: [Piper PA-28-181](https://openairdocs.org/model/piper-pa-28-181) (registry code 7102807) (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: 28-7990139 - Airframe hours: 6813 - Engines: LYCOMING O-360 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Triad Air Inc, doing business as Piedmont Flight Training - Registered owner: Triad Air Inc - Airworthiness certificate: Standard, Normal - Last inspection: Annual, January 11, 2013, 51 hours before - Departed: AVL, Asheville, NC - Destination: INT, Winston Salem, NC - Flight plan: Unknown - Airport: INT, Smith Reynolds Airport, runway 22, 3,938 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 26; injuries: none; private; airplane ratings: single-engine land; medical: class 1, with waivers/limitations; last flight review October 12, 2012; seat: left; flight hours: 102 total, 87 in this make and model, 43 as pilot in command, 19 in the last 90 days, 14 in the last 30 days, 1 in the last 24 hours - Flight instructor; age 43; injuries: none; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review October 4, 2012; seat: right; flight hours: 2,300 total, 64 in this make and model, 2,200 as pilot in command, 33 in the last 90 days, 2 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 200° at 10 knots, gusting 17 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 39 °F - Altimeter: 30.12 inHg - Observed at: INT ## 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 20130407006659A](https://openairdocs.org/incident/20130407006659A), Apr 7, 2013: Piper PA-28-181, Winston Salem, NC, Substantial damage. Aircraft landed at kint during 8 to 12 knot cross wind. Aircraft landed and began rollout, started to settle on and compress struts when the right landing gear… ## Docket (9 files) The files NTSB released with the investigation on June 18, 2013, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=86630. 5.1 MB in all. - Materials Laboratory 15 - Factual Report 13-039 (w/ 9 images) (item 1, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392759&FileExtension=.PDF&FileName=Materials%20Laboratory%2015%20-%20Factual%20Report%2013-039%20(w%2F%209%20images)-Master.PDF - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 2, .PDF, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392786&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Interview Summary (item 3, .PDF, 23 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40393247&FileExtension=.PDF&FileName=Interview%20Summary-Master.PDF - Correspondence From FAA Inspector (item 4, .PDF, 21 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40393709&FileExtension=.PDF&FileName=Correspondence%20From%20FAA%20Inspector-Redacted.PDF - Weather Report (item 5, .PDF, 15 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392788&FileExtension=.PDF&FileName=Weather%20Report-Master.PDF - Excerpt From Airplane Maintenance Manual (item 6, .PDF, 65 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40393248&FileExtension=.PDF&FileName=Excerpt%20From%20Airplane%20Maintenance%20Manual-Master.PDF - Evidence Control Form (item 7, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392805&FileExtension=.PDF&FileName=Evidence%20Control%20Form-Master.PDF - Photograph # 1: Right Main Landing Gear Skid Mark And Scrape on Runway (Photo Courtesy of Operator) (item 8, .PDF, 387 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392790&FileExtension=.PDF&FileName=Photograph%20%23%201%3A%20%20Right%20Main%20Landing%20Gear%20Skid%20Mark%20And%20Scrape%20on%20Runway%20(Photo%20Courtesy%20of%20Operator)-Master.PDF - Photograph # 2: Right Wing Damage (Photo Courtesy of FAA) (item 9, .PDF, 136 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40392791&FileExtension=.PDF&FileName=Photograph%20%23%202%3A%20%20Right%20Wing%20Damage%20(Photo%20Courtesy%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.