# NTSB LAX97LA245: Classic Waco YMF-5, N553T, Pahoa, HI, July 16, 1997 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: July 16, 1997, 11:50 local (21:50 UTC) - Place: Pahoa, HI - Coordinates: 19.489498, -154.939971 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=19.4895&lon=-154.9400&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 1 minor, 2 uninjured - Status: Completed, report January 7, 1998 - Report: Approved by Office Director - NTSB case key (mKey): 29838 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX97LA245 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/29838/pdf - Page: https://openairdocs.org/ntsb/LAX97LA245 ## Probable cause Loss of the propeller retaining nut and associated hardware for undetermined reasons. A factor in the accident was the lack of suitable terrain for a forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Propeller failure/malfunction, cruise - propeller system/accessories,prop blade retention - separation (cause) - reason for occurrence undetermined (cause) - Forced landing, emergency descent/landing - terrain condition - none suitable (contributing factor) - In flight collision with terrain/water, emergency landing - terrain condition - rock(s)/boulder(s) ## Analysis In cruise during a for-hire sightseeing flight over a volcanic crater the aircraft sustained an in-flight separation of the propeller. The pilot made a forced landing in a lava field. The pilot reported that there was no unusual vibration or other warning prior to the propeller separating from the aircraft. The pilot further reported that he personally inspected the propeller, retaining nut, and clevis pin the morning of the accident. Two prior flights were successfully completed and the accident occurred on the third flight of the day. During the aircraft recovery efforts, the propeller was found over a mile from the aircraft point of rest. Propeller hub/attachment components consisting of the forward cone, a snap ring, the hub retaining nut, and the clevis pin were not located. An examination of the aircraft was conducted by FAA Airworthiness inspectors who reported that nothing unusual was noted to the crankshaft splines, threaded front end (where the retaining nut is installed), or the grooves for the clevis pin. The examining inspectors stated that, 'apart from impact damage there was no other evident damage to propeller shaft that would suggest premature failure of propeller shaft that would cause departure of propeller from aircraft.' ## Factual narrative On July 16, 1997, at 1150 hours Hawaiian standard time, a Classic Aircraft Corporation Waco YMF-5, N553T, sustained an in-flight separation of the propeller during cruise flight near the Pu`u `O`o volcanic crater and made a forced landing in a lava field close to Pahoa, Hawaii. The aircraft was owned by Classic Aircraft Corporation and was operated on a 14 CFR Part 91 local area for-hire sightseeing flight. The aircraft incurred substantial damage. The commercial pilot and one passenger were not injured, however, the remaining passenger received minor injuries. Visual meteorological conditions prevailed at the time of the accident. The pilot reported in a verbal statement to Federal Aviation Administration (FAA) inspectors that there was no unusual vibration or other warning prior to the propeller separating from the aircraft. In his written statement, the pilot further reported that he personally inspected the propeller, retaining nut, and clevis pin the morning of the accident. Two prior flights were successfully completed, and the accident occurred on the third flight of the day. During the aircraft recovery efforts, the propeller was found over a mile from the aircraft point of rest. Propeller hub/attachment components consisting of the forward cone, a snap ring, the hub retaining nut, and the clevis pin were not located. An examination of the aircraft was conducted by FAA Airworthiness inspectors from the Honolulu Flight Standards District Office following recovery of the wreckage. The inspectors reported that "nothing unusual" was noted to the crankshaft splines, threaded front end (where the retaining nut is installed), or the grooves for the clevis pin. The examining inspectors stated that, "apart from impact damage there was no other evident damage to propeller shaft that would suggest premature failure of propeller shaft that would cause departure of propeller from aircraft." The only specific discrepancy the FAA inspectors found was that the propeller on the aircraft was not the one listed in the maintenance records as being installed on the aircraft. According to the maintenance records, propeller serial number AC0217 was supposed to be the one installed at the time of the accident. Serial number AC9806 was stamped on the propeller recovered from the accident scene. ## Aircraft - Registration: N553T (not matched to a registry record) - Reported make and model: Classic Aircraft Corp. WACO YMF-5 - Category: Airplane - Serial number: 50 - Airframe hours: 2082 - Engines: Jacobs 755-B2M 275 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Registered owner: Classic Aviation Corp - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, May 29, 1997, 50 hours before - Departed: ITO, HILO, HI - Airport: ITO, Hilo International ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: rear; flight hours: 7,686 total, 898 in this make and model, 7,455 as pilot in command, 99 in the last 90 days, 34 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 40° at 8 knots - Visibility: 15 statute miles - Lowest ceiling: 2,500 ft broken - Temperature: 84 °F, dew point 70 °F - Altimeter: 30.00 inHg - Observed at: ITO, 18 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 19970716018599A](https://openairdocs.org/incident/19970716018599A), Jul 16, 1997: Waco YMF, Hilo, HI, Substantial damage. Propeller separated at cruis prop not one that was supposed to be installed. 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.