# NTSB WPR14LA179: Coulter Hugh Clarke Pulsar XP Series I, N452PC, Bremerton, WA, April 30, 2014 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: April 30, 2014, 10:55 local (17:55 UTC) - Place: Bremerton, WA - Coordinates: 47.494998, -122.774719 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.4950&lon=-122.7747&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report November 19, 2015 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 89153 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR14LA179 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/89153/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=89153 - Page: https://openairdocs.org/ntsb/WPR14LA179 ## Probable cause Fatigue failure of the nose landing gear retention and pivot shaft, which resulted in the in-flight separation of the nose gear wheel and tire assembly. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Landing gear system: nose/tail gear strut/axle](https://openairdocs.org/ntsb-findings/01023222): Aircraft › Aircraft systems · Fatigue/wear/corrosion (probable cause); cases with it: [Coulter Hugh Clarke PULSAR XP SERIES I, 1 case](https://openairdocs.org/ntsb-findings/01023222/cases.md?model=056041T), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/01023222/cases.md) - [Landing gear system: nose/tail gear strut/axle](https://openairdocs.org/ntsb-findings/01023222): Aircraft › Aircraft systems · Failure (probable cause); cases with it: [Coulter Hugh Clarke PULSAR XP SERIES I, 1 case](https://openairdocs.org/ntsb-findings/01023222/cases.md?model=056041T), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/01023222/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Aircraft structural failure](https://openairdocs.org/ntsb-events/337) (defining event); cases with it: [Coulter Hugh Clarke PULSAR XP SERIES I, 1 case](https://openairdocs.org/ntsb-events/337/sequence.md?model=056041T), [All aircraft, 290 cases](https://openairdocs.org/ntsb-events/337/sequence.md) - [Takeoff: Part(s) separation from AC](https://openairdocs.org/ntsb-events/338); cases with it: [Coulter Hugh Clarke PULSAR XP SERIES I, 1 case](https://openairdocs.org/ntsb-events/338/sequence.md?model=056041T), [All aircraft, 563 cases](https://openairdocs.org/ntsb-events/338/sequence.md) ## Analysis During takeoff, the builder/owner/pilot of the experimental kit-built airplane did not notice any abnormalities. While airborne, he received a radio call from personnel at the airport advising him that a nose landing gear wheel and tire assembly had been found on the runway; they stated that they believed it had separated from his airplane. The pilot flew back to the airport and conducted a low pass, and the airport personnel confirmed that the airplane was missing its nose gear wheel and tire assembly. After flying for about 30 minutes so appropriate emergency services preparations could be made, the pilot landed the airplane. During the landing roll, the airplane settled on its nose, which resulted in substantial damage to the firewall. Examination of the airplane revealed that the steel shaft that attached the nose gear fork to the gear leg and functioned as its pivot axis had failed in reverse (bi-directional) bending fatigue. The underlying reason(s) for the fatigue failure could not be not determined. The pilot reported that similar previous failures had occurred on this model airplane. Because the kit manufacturer was no longer in business, some airplane owners had developed their own modifications to the nose gear assembly, but the accident airplane's nose gear had not been modified. ## Factual narrative According to the pilot, he completed construction of, and first flew, the airplane in 1998, and had put about 811 hours on it since then. The airplane was equipped with a Rotax 912UL series engine. About 2 days after the accident, the pilot was informed by another Pulsar operator that there were five previous events of NLG separations on Pulsar airplanes. Reportedly, a new NLG fitting had been designed by another owner to eliminate the underlying problem, which was traced to a corroded attach bolt that was difficult to access or inspect. Also reportedly, these failures only affected Pulsar "Series 1" airplanes, which was the same model as the pilot's airplane. Because the airplane kit manufacturer was no longer in business, the investigation did not obtain any additional information regarding the NLG modification. On April 30, 2014, about 1055 Pacific daylight time, an experimental amateur-built Pulsar XP, N452PC, sustained substantial damage on landing at Bremerton National airport (PWT), Bremerton, Washington. The pilot-owner was not injured. The personal flight was conducted under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the flight. According to the pilot, he was also the builder of the kit airplane. The airplane was based at PWT. The pilot took off about 1000 for a local flight. While airborne, he received a radio call from Avian Flight Center, a fixed base operator (FBO) at PWT. FBO personnel informed him that they had been made aware that a passer-by had seen something fall from an airplane, which was subsequently identified as a nose landing gear (NLG) wheel and tire assembly, and that the FBO believed that the NLG components possibly belonged to N452PC. The pilot returned to PWT and conducted a flyby, to allow the FBO personnel to examine the airplane. They confirmed that N452PC had lost its NLG wheel and tire assembly. The FBO then coordinated with the pilot to postpone landing until the airport could be closed to other traffic, and fire/rescue personnel could be present. After waiting about 30 minutes, the pilot was given permission to land. He landed with full flaps, as slowly as he could. The airplane landed normally, settled on the NLG strut, and stopped on the runway. The 1055 PWT automated weather observation included winds from 030 degrees at 8 knots, visibility 10 miles, clear skies, temperature 21 degrees C, dew point 6 degrees C, and an altimeter setting of 30.38 inches of mercury. Federal Aviation Administration (FAA) records indicated that the pilot held a private pilot certificate with an airplane single engine land rating. According to information provided by the pilot, he had approximately 884 total hours of flight experience, including approximately 811 hours in the accident airplane make and model. His most recent flight review was completed in June 2012, and his most recent FAA third-class medical certificate was issuedin April 2003. The pilot was operating the airplane in accordance with the FAA sport pilot medical certification criteria. The airplane came to rest upright, about 150 feet beyond the numbers of runway 2, just left of the centerline. The NLG strut and lower cowl were crushed and scraped, both blades of the wood propeller were fractured, and the firewall was fractured in at least two locations. Examination of the wreckage by FAA personnel revealed that the pivot shaft that enabled the nose landing gear (NLG) wheel and tire assembly to caster for directional control had fractured, and that fracture allowed the NLG fork to depart the airplane during takeoff. Examination of photographs of the fracture end of the pivot shaft by the investigator-in-charge and a metallurgist at the NTSB materials laboratory indicated that the fracture patterns were consistent with reversed bending (bi-directional) fatigue. According to the builder/owner/pilot, the shaft was a solid 4130 steel rod that nested and was welded into the tubular steel nose gear leg, and on which the NLG fork assembly was mounted and rotated. The shaft fractured just inside the lower end of the NLG leg tube. ## Aircraft - Registration: [N452PC](https://openairdocs.org/aircraft/N452PC), registered now, S/N 452, built 1998 (OpenAirDocs) - Reported make and model: COULTER HUGH CLARKE PULSAR XP SERIES I - Registry model: [Coulter Hugh Clarke PULSAR XP SERIES I](https://openairdocs.org/model/coulter-hugh-clarke-pulsar-xp-series-i) (registry code 056041T) (OpenAirDocs) - Registry engine: [Bombardier ROTAX (ALL)](https://openairdocs.org/engine/bombardier-rotax-all) (registry code 09050, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 452 - Year built: 1998 - Airframe hours: 811 - Engines: Rotax 912UL 80 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, June 19, 2013, 22 hours before - Departed: PWT, Bremerton, WA - Destination: PWT, Bremerton, WA - Airport: PWT, Bremerton, runway 2, 6,000 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 81; injuries: none; private; airplane ratings: single-engine land; medical: sport pilot; last flight review June 15, 2012; seat: left; restraint: 3-point; flight hours: 884 total, 811 in this make and model, 848 as pilot in command, 6 in the last 90 days, 3 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 30° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 70 °F, dew point 43 °F - Altimeter: 30.37 inHg - Observed at: PWT ## 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 20140430005429A](https://openairdocs.org/incident/20140430005429A), Apr 30, 2014: Coulter Hugh Clarke PULSAR XP SERIES I, Bremerton, WA, Substantial damage. During take-off from the Bremerton internation airport (pwt) at around 1050 am, located in Bremerton, WA. The aircraft lost it's nose wheel assembly. The pilot… ## Docket (6 files) The files NTSB released with the investigation on October 27, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=89153. 4.8 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433193&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation - Pilot (item 2, .PDF, 47 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433194&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Pilot-Master.PDF - Airplane Information (item 3, .PDF, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433195&FileExtension=.PDF&FileName=Airplane%20Information-Master.PDF - Record of Communication Materials Laboratory (item 4, .PDF, 54 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433198&FileExtension=.PDF&FileName=Record%20of%20Communication%20Materials%20Laboratory-Master.PDF - Nose Gear Modification Information (item 5, .PDF, 362 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433199&FileExtension=.PDF&FileName=Nose%20Gear%20Modification%20Information-Master.PDF - METARs (item 6, .PDF, 25 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433205&FileExtension=.PDF&FileName=METARs-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.