# NTSB ERA15LA225: Piper PA44, N2163F, Miami, FL, May 23, 2015 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: May 23, 2015, 16:05 local (20:05 UTC) - Place: Miami, FL - Coordinates: 25.643054, -80.433052 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=25.6431&lon=-80.4331&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: 3 uninjured - Status: Completed, report July 11, 2016 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - SAIBs cited in the narratives: [SAIB CE-10-30](https://openairdocs.org/saib/CE-10-30) (OpenAirDocs) - NTSB case key (mKey): 91259 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA15LA225 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91259/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91259 - Page: https://openairdocs.org/ntsb/ERA15LA225 ## Probable cause The failure of the nose landing gear upper drag link knee bolt due to reverse-bending fatigue, which was likely preceded by excessive bearing wear due to reasons that could not be determined based on the available evidence. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: gear extension and retract sys](https://openairdocs.org/ntsb-findings/01023230): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Piper PA-44-180, 9 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md?model=7104402), [All aircraft, 416 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md) - [Landing gear system: gear extension and retract sys](https://openairdocs.org/ntsb-findings/01023230): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Piper PA-44-180, 9 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md?model=7104402), [All aircraft, 416 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md) - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined; cases with it: [Piper PA-44-180, 6 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=7104402), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094) (defining event); cases with it: [Piper PA-44-180, 11 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=7104402), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md) ## Analysis The flight instructor reported that the student pilot's approach and landing during the instructional flight were normal. During the landing roll, the nose landing gear (NLG) collapsed, which resulted in structural damage to the airframe. Examination of the NLG revealed that an upper drag link and associated knee bolt were broken. Subsequent examination of the upper drag link revealed that it had failed due to overstress; however, the knee bolt had failed due to reverse-bending fatigue from relatively high-cyclic stresses. Given the failure location, it is likely that excessive wear in the bearing preceded the bolt failure. The airplane manufacturer had issued a service bulletin applicable to the accident airplane, which recommended the inspection of the NLG drag link assembly and replacement of the associated knee bolt at 500-hour intervals. Further, the Federal Aviation Administration subsequently issued a special airworthiness bulletin, which recommended that the NLG drag link assembly inspection and knee bolt replacement interval be reduced to 400 hours time in service (TIS) for airplanes that experienced greater-than-normal landing cycles per flight hour, including airplanes used for flight school operations like the accident airplane. A review of the airplane's maintenance records revealed that the failed knee bolt was replaced about 386 hours TIS before the accident. Although the records indicated that the flight school followed the 500-hour interval not the 400-hour interval, the bolt had been replaced at less hours TIS than the recommended interval; therefore, the reason for the premature excessive wear could not be determined. ## Factual narrative On May 23, 2015, about 1605 eastern daylight time (EDT), a Piper PA-44-180, N2163F, was substantially damaged after the nose landing gear collapsed while landing at Miami Executive Airport (TMB), Miami, Florida. The private pilot-rated student, an air transport-rated flight instructor, and one passenger were not injured. The airplane was operated by Pilot Training Center LLC under the provisions of Title 14 Code of Federal Regulations Part 91 as an instructional flight. Day, visual meteorological conditions prevailed, and no flight plan was filed. The flight originated at West Palm Beach, Florida (OBE) at 1530.The flight instructor reported that his student performed a normal approach and landing to runway 9R at TMB. During the landing roll, the nose gear collapsed. The airplane came to a stop on the runway and the occupants exited the airplane. A Federal aviation Administration (FAA) inspector responded to the accident site and examined the airplane. The nose gear was collapsed into the wheel well, and the main gear remained extended. The nose gear upper drag link and associated knee bolt were broken. The pitot tube on the left wing was pushed up into the wing structure, resulting in structural damage. Both propellers struck the runway and all blades were damaged. The nose landing gear upper drag link and knee bolt were removed and forwarded to the NTSB Materials Laboratory for examination and analysis. The examination of the upper drag link revealed matte gray and rough fracture surfaces consistent with overstress. The associated knee bolt bushing was cracked and deformed on both sides. The examination revealed that the knee bolt was fractured near the middle of the grip section. The surface of the shank was dark gray in color and showed no evidence of circumferential scoring damage. The head of the bolt was marked "NAS 6204-270 CS." The fracture surface of the knee bolt was examined under magnification. Portions of the fracture surface had a lighter gray color with curving crack arrest lines, consistent with fatigue. The fatigue regions emanated from origins on opposite sides of the bolt, a feature consistent with reverse bending fatigue. The fatigue region showed ratchet marks and relatively rough texture, features consistent with fatigue crack initiation and growth under relatively high cyclic stress. Piper Service Bulletin (SB) 1156, issued April 7, 2005, required periodic replacement of the nose gear drag link knee bolt on certain Piper aircraft, including the PA-44-180. The SB was issued in response to circumferential score marks that could develop in the bolt over time, causing stress concentrations to develop that could eventually lead to failure of the bolt. The SB called for inspections of the bushings in the knee joint for the upper and lower drag links for serviceability and for the knee bolt to be replaced at 500-hour intervals. Although SB 1156 called for a National Aerospace Standard (NAS) 464P4 bolt, the bolt installed in theaccident airplane was a NAS6204 bolt. The NAS6204 bolt met the size and harness requirements of the SB. Since issuance of the SB, the NAS464 bolt was discontinued for new designs and replaced with the NAS6203 through 6220 bolts. On May 4, 2010, the FAA issued Special Airworthiness Information Bulletin (SAIB) CE-10-30 in response to another Piper PA-44-180 airplane that experienced a nose gear collapse during landing due to a fractured nose gear drag link knee bolt. Additionally, it was noted the airplane from SAIB CE-10-30 was used in flight school operations where higher than normal landing cycles were common. In SAIB CE-10-30, the FAA recommended that for airplanes that experience greater than normal landing cycles per flight hour, the inspections of the nose gear drag link assembly and knee bolt replacement per Piper SB 1156 should be reduced to 400 hours time in service (TIS). According to maintenance records for the accident airplane, the nose gear assembly was replaced as noted in an entry dated May 15, 2014. According to correspondence with maintenance personnel for the airplane, the nose assembly was replaced due to a collapse of the nose gear where the knee bolt was broken. According to the May 15, 2014, log book entry, the repair incorporated Piper SB 1156 and also noted that SB 1156 was to be repeated every 500 hours TIS. At the time of the last log book entry on May 20, 2015, which was a 100-hour inspection, the airplane had accrued 386.2 hours TIS since the May 15, 2014 entry. According to FAA records, the accident airplane has been registered to Pilot Training Center, LLC, since April 25, 2012. No reference to FAA CE-10-30 or any reduced interval for inspection and knee bolt replacement on airplanes used in flight training operations was noted in the log book entry on May 15, 2014. ## Aircraft - Registration: [N2163F](https://openairdocs.org/aircraft/N2163F), registered now, S/N 44-7995167, built 1978 (OpenAirDocs) - Reported make and model: PIPER PA44 (180) - Registry model: [Piper PA-44-180](https://openairdocs.org/model/piper-pa-44-180) (registry code 7104402) (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: 44-7995167 - Year built: 1978 - Airframe hours: 10354 - Engines: LYCOMING O-360 SER 180 horsepower reciprocating; LYCOMING O-360 SER 180 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Pilot Training Center LLC - Registered owner: Pilot Training Center LLC - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 20, 2015 - Departed: OBE, West Palm Beach, FL - Destination: TMB, Miami, FL - Flight plan: VFR - Airport: TMB, Miami Executive, runway 09R, 5,999 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Student pilot; age 28; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review April 6, 2015; seat: left; restraint: 3-point; flight hours: 253 total, 20 in this make and model, 135 as pilot in command, 20 in the last 90 days, 7 in the last 30 days, 2 in the last 24 hours - Flight instructor; age 31; injuries: none; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review August 3, 2013; seat: right; restraint: 3-point; flight hours: 4,600 total, 125 in this make and model, 3,800 as pilot in command, 210 in the last 90 days, 90 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 110° at 12 knots - Visibility: 10 statute miles - Temperature: 90 °F, dew point 72 °F - Altimeter: 30.14 inHg - Observed at: TMB ## 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 20150523008719A](https://openairdocs.org/incident/20150523008719A), May 23, 2015: Piper PA-44-180, Tamiami, FL, Substantial damage. On may 23rd 2015 at 1605 eastern standard time, a Piper seminole PA-44-180, N2163F, registered to pilot training center, LLC was operating out of… ## Docket (6 files) The files NTSB released with the investigation on May 24, 2016, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91259. 2.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 648 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440352&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Excerpts - Maintenance Logbooks (item 2, .PDF, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440353&FileExtension=.PDF&FileName=Excerpts%20-%20Maintenance%20Logbooks-Master.PDF - Materials Laboratory Factual Report 15-105 (item 3, .PDF, 4 photos, 512 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440354&FileExtension=.PDF&FileName=Materials%20Laboratory%20Factual%20Report%2015-105-Master.PDF - Evidence Control (item 4, .PDF, 142 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440355&FileExtension=.PDF&FileName=Evidence%20Control-Master.PDF - FAA SAIB CE-10-30 (item 5, .PDF, 32 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440356&FileExtension=.PDF&FileName=FAA%20SAIB%20CE-10-30-Master.PDF - FAA Photo (item 6, .PDF, 1 photo, 64 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40440357&FileExtension=.PDF&FileName=FAA%20Photo-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.