# NTSB MIA96LA173: Piper PA-23-150, N3061P, Knoxville, TN, July 2, 1996 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: July 2, 1996, 13:50 local (17:50 UTC) - Place: Knoxville, TN - Coordinates: 35.910118, -83.869758 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.9101&lon=-83.8698&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report August 25, 1997 - Report: Approved by Office Director - NTSB case key (mKey): 38041 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA96LA173 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38041/pdf - Page: https://openairdocs.org/ntsb/MIA96LA173 ## Probable cause Fatigue failure of the blade No. 1 hub arm of the left propeller. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Propeller failure/malfunction, takeoff - initial climb - propeller system/accessories,hub - fatigue (cause) - propeller system/accessories,blade - separation - Nose gear collapsed, emergency descent/landing ## Analysis Shortly after takeoff, about 50-75 feet above the runway, one of the two propeller blades from the left propeller separated. The FAA designee took the controls and landed the airplane with the landing gear extended on grass adjacent to the runway. The airplane traveled off the runway and came to rest upright with the nose landing gear collapsed. Examination of the left propeller revealed that the blade No. 1 hub arm failed due to fatigue. Review of the propeller maintenance records revealed that the propeller was last overhauled on October 18, 1985, and had accumulated a total time of 2,979.7 hours since manufacturer and 963.2 hours since overhaul. ## Factual narrative On July 2, 1996, about 1350 eastern daylight time, a Piper PA-23-150, N3061P, privately registered and operated by the Knoxville Flight Training Center, Inc., was substantially damaged during an aborted takeoff from the Knoxville Downtown Island Airport, Knoxville, Tennessee. Visual meteorological conditions prevailed at the time and no flight plan was filed for the 14 CFR Part 91 checkride flight. The commercial-rated pilot-in-command and FAA designee were not injured. The flight was originating at the time of the accident. The designee stated that there was no unusual engine vibration from the left engine while taxiing or during the left engine run-up before takeoff. After rotation about 50-75 feet above the ground with the applicant manipulating the controls, he first heard a loud sound then felt a vibration from the left engine. He then took the controls and landed the airplane on grass adjacent to the runway which collapsed the nose landing gear. The airplane slid to a stop with the nose section of the airplane down an embankment of a river on the airport property. Visual examination of the left propeller revealed 1 blade and clamp separated. Examination of the propeller revealed that the blade No. 1 separated with the clamp secured around the blade. The blade retention lip of the propeller hub was observed to be fractured. Metallurgical examination of the fracture surface of the retention lip revealed that it failed due to fatigue. Corrosion was not observed on the fracture surface. Review of the left propeller maintenance records revealed that it was last overhauled on October 18, 1985. The propeller had accumulated about 963.2 hours since overhaul and 2, 979.7 hours since manufacture at the time of the failure. According to FAA records, the airplane had not previously been involved in an accident or incident. According to a Hartzell Service Letter 61S (non-mandatory compliance), dated December 10, 1993, indicates that the accident model propeller is to be overhauled every 1,000 hours or 60 calendar months. The non-retained propeller components were released to Mr. John McConkey, President of the Knoxville Flight Training Center, on July 10, 1996. The retained propeller components were released to Mr. Randy Duncan, Flight Instructor/Manager of the Knoxville Flight Training Center, on March 11, 1997. ## Aircraft - Registration: [N3061P](https://openairdocs.org/deregistered/N3061P-2012-11-06), registration cancelled 2012-11-06, S/N 23-977, built 1957 (OpenAirDocs) - Reported make and model: Piper PA-23-150 - Registry model: [Piper PA-23-150](https://openairdocs.org/model/piper-pa-23-150) (registry code 7102303) (OpenAirDocs) - Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 23-977 - Airframe hours: 2980 - Engines: Lycoming O-320-A1A 150 horsepower reciprocating - Damage: Substantial damage - Flight: Part 91 - Operator: Knoxville Flight Training Ctr - Registered owner: William R. Mahafey Jr. - Airworthiness certificate: Standard, Normal - Last inspection: Annual, June 1, 1996, 14 hours before - Departed: DKX - Airport: DKX, Knoxville Downtown Island, runway 26, 3,497 × 75 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 42; flight instructor, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: right; flight hours: 724 total, 13 in this make and model, 432 as pilot in command, 62 in the last 90 days, 35 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 12 knots, gusting 16 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 91 °F, dew point 68 °F - Altimeter: 29.00 inHg - Observed at: DKX, 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 19960702015809A](https://openairdocs.org/incident/19960702015809A), Jul 2, 1996: Piper PA23150, Knoxville, TN, Substantial damage. Left engine prop blade separated CFI aborted. Landed on grass down embankment. Prop hug fractured. 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.