# NTSB LAX99LA061: Ercoupe 415-C, N99371, San Ysabel, CA, December 30, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: December 29, 1998, 16:45 local (Dec 30, 1998, 00:45 UTC) - Place: San Ysabel, CA - Coordinates: 33.180107, -116.72908 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.1801&lon=-116.7291&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 16, 2001 - Report: Approved by Office Director - NTSB case key (mKey): 45528 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX99LA061 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45528/pdf - Page: https://openairdocs.org/ntsb/LAX99LA061 ## Probable cause A fatigue fracture of the crankshaft and the resulting separation of the propeller. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - engine assembly,crankshaft - fatigue (cause) - engine assembly,crankshaft - fractured (cause) - propeller system/accessories - separation - Forced landing, emergency descent/landing - On ground/water encounter with terrain/water, emergency landing - terrain condition - rough/uneven (contributing factor) - Nose gear collapsed, landing - roll - landing gear,nose gear - overload ## Analysis In cruise flight at 4,500 feet, the pilot added power as the terrain began to rise, then the engine started to vibrate. As the pilot looked down to check the mixture and carburetor heat, the vibration intensified. The crankshaft fractured and the propeller separated from the airplane. The pilot subsequently made a forced landing on uneven terrain and the nose gear collapsed. Metallurgical laboratory examination of the remaining crankshaft piece determined the crankshaft separated forward of the oil-slinger flange due to fatigue. The fatigue region had an origin point in an area mechanically damaged during the crankshaft failure. ## Factual narrative On December 29,1998, about 1645 hours Pacific standard time, an Ercoupe 415-C, N99371, incurred an in-flight failure of the crankshaft and subsequent separation of the propeller near San Ysabel, California. The airplane sustained substantial damage when the nose gear collapsed during the off-field forced landing. The private pilot, the sole occupant, was operating the borrowed airplane under the provisions of 14 CFR Part 91, and was not injured. The local personal flight originated from Ramona, California, about 1630. Visual meteorological conditions prevailed and no flight plan was filed. The pilot stated he was in cruise flight at 4,500 feet and approaching rising terrain. As he added power to climb, the engine started to vibrate. He looked down to check the mixture and carburetor heat and felt bad vibrations and heard a noise. He saw a flash out of the corner of his left eye, followed by a bang on the left wing. He noticed the top leading edge of the left wing was dented, heard a high whining sound and saw that the propeller had separated. He set up for best glide speed, looked for a place to land, and broadcast an emergency call on the common traffic advisory frequency. He estimated his speed at touchdown was just above stall speed. The left main landing gear touched down first, followed by the nose gear, then the right main gear. The terrain was uneven and the nose gear eventually collapsed. He estimated the airplane stopped within 100 feet. He turned the emergency locator transmitter (ELT) off and tried to radio for help. It did not work, so he secured the cockpit and walked to a farmhouse. Examination of the remaining crankshaft piece by the Safety Board's materials laboratory determined the crankshaft separated forward of the oil-slinger flange. The fracture spiraled around the crankshaft and suffered a large amount of mechanical damage. The laboratory's factual report noted a fatigue region intersected this damaged area. The laboratory determined from the crack arrest markings that the cracking initiated from a location approximately midway between the interior and exterior surfaces of the crankshaft wall. The fatigue region was flat and contained areas of multiple crack arrest marks. This fatigue region propagated through approximately 270 degrees of the circumference of the part. The remainder of the fracture surface, located between the end of the fatigue region and the origin, was rough and oriented on an angle. The external surface of the crankshaft revealed scattered corrosion pits on the fractured end and a region of fretting. The fretting was adjacent to a keyway used to secure the propeller to the hub. The report estimated the position of the fatigue initiation area approximately corresponded to the depth and location of the edge of the keyway slot. ## Aircraft - Registration: [N99371](https://openairdocs.org/deregistered/N99371-2013-04-10), registration cancelled 2013-04-10, S/N 1994, built 1946 (OpenAirDocs) - Reported make and model: Ercoupe (Eng & Research Corp.) 415-C - Registry model: [Ercoupe 415-C](https://openairdocs.org/model/ercoupe-415-c) (registry code 0420322) (OpenAirDocs) - Registry engine: [Continental A&C75 series](https://openairdocs.org/engine/continental-a-c75-series) (registry code 17005, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 1994 - Airframe hours: 2559 - Engines: Continental C-85 85 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Orlando Enriquez - Airworthiness certificate: Standard, Normal - Last inspection: Annual, October 1, 1998, 7 hours before - Departed: RNM, RAMONA, CA ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 54; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 394 total, 126 in this make and model, 357 as pilot in command, 32 in the last 90 days, 26 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Dusk - Wind: calm - Visibility: 6 statute miles - Lowest ceiling: none - Temperature: 55 °F, dew point 39 °F - Altimeter: 29.00 inHg - Observed at: RNM, 13 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 19981229045089A](https://openairdocs.org/incident/19981229045089A), Dec 29, 1998: Univar 415C, Santa Ysabel, CA, Substantial damage. (.19) On December 29, 1998, about 1645 pacific standard time, an Ercoupe 415-C, N99371, incurred an inflight separation of the propeller near san Ysabel,… 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.