# NTSB LAX02LA279: Lockamy Sonex, N164JL, Oxnard, CA, September 8, 2002 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: September 8, 2002, 11:36 local (18:36 UTC) - Place: Oxnard, CA - Coordinates: 34.200832, -119.207221 - Nearby events: https://openairdocs.org/map.md?lat=34.2008&lon=-119.2072&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report September 29, 2004 - Report: Approved by Office Director - Parties: Federal Aviation Administration - NTSB case key (mKey): 55653 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX02LA279 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/55653/pdf - Page: https://openairdocs.org/ntsb/LAX02LA279 ## Probable cause the loosening of the tapered spacer, which resulted in the propeller hub separating from the crankshaft. A factor in the accident was the unsuitable terrain for landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, takeoff - initial climb - engine assembly,other - loose (cause) - propeller system/accessories,hub - disconnected (cause) - Forced landing, emergency landing after takeoff - In flight collision with terrain/water, emergency landing after takeoff - unsuitable terrain or takeoff/landing/taxi area - encountered (contributing factor) - terrain condition - ground ## Analysis The experimental airplane experienced a propeller drive shaft failure and collided with the terrain during a forced landing at an airport. During the initial climb, about 300 to 400 feet above ground level, the engine surged and the airplane could not sustain lift. The engine was still producing power, but failed to distribute that power to the propeller. With a lemon grove directly ahead, the pilot opted to turn back to the runway to land. As he began a left turn toward the runway, the left wing impacted the dirt and the airplane "cartwheeled." Examinations revealed that the propeller hub had separated from the crankshaft. The tapered spacer, attached to crankshaft, had loosened. This instantaneous torque load to the crankshaft resulted in the propeller hub separating from the remaining taper, and the bolt unscrewing from the crankshaft. ## Factual narrative On September 8, 2002, at 1136 Pacific daylight time, a Lockamy Sonex experimental airplane, N164JL, collided with the terrain during a forced landing at the Oxnard Airport, Oxnard, California. The pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. The private pilot, the sole occupant, sustained serious injuries; the airplane sustained substantial damage. The personal local flight was originating from Oxnard. Visual meteorological conditions prevailed, and a flight plan had not been filed. During a telephone conversation with a National Transportation Safety Board investigator, the pilot stated that while in the initial climb, about 300 to 400 feet above ground level, the engine surged and the airplane could not sustain lift. The engine was still producing power, but failed to distribute that power to the propeller. With a lemon grove directly ahead of him, the pilot opted to turn back to the runway to land. As he began a left turn toward the runway, the left wing impacted the dirt and the airplane "cartwheeled." He felt a violent reaction in the cockpit as he was thrown from the airplane. The pilot further stated that, while doing an engine teardown, he discovered that the propeller hub had separated from the crankshaft. The non-aircraft grade bolt that connected the hub to the crankshaft had "backed out" leaving the propeller spinning freely. He also noted that 2 weeks prior to the accident he had a similar propeller hub to crankshaft separation problem, at which time he removed the propeller hub and reattached it. He thought that the bolt's threads were loaded improperly and the bolt was not sufficient in transferring the load. The Volkswagen Type 4 engine crankshaft end has a conically tapered end with a shoulder reduction from the crankshaft diameter that in an automotive application contains a press fit pulley. To adapt the engine to aircraft application, a conically tapered metal sleeve (the kit manufacturer refers to this as a "tapered spacer"), which is seated on the shoulder to bring the diameter of the shaft end to a constant taper for the propeller hub to fit over. Great Plains Aircraft, a distributor of the Volkswagen Type 4 engine, released a Service Bulletin after investigating this and a similar accident. Their examinations revealed that the bolt did not fail; rather, the bolt loosening and backing out is a result of the tapered spacer spinning on the shaft. They further stated that normally about 51 percent of torque is transmitted through the tapered spacer to the tapered crankshaft. They noted that if the tapered spacer breaks loose, the entire load is distributed to the rest of the crankshaft. The length of the tapered spacer is about 1.250 inches, with the remaining length of the crankshaft/propeller hub taper about 1.200 inches. When the separation of the spacer occurs, the instantaneous torque load to the crankshaft results in the propeller hub separating from the remaining taper, and the bolt unscrewing from the crankshaft. The pilot failed to submit a pilot/operator report, NTSB Form 6120.1/2. According to Federal Aviation Administration Advisory Circular AC 20-27F, Certification and Operation of Amateur-Built Aircraft, "Amateur builders are free to develop their own designs or build from existing designs. We do not approve these designs and it would be impractical to develop design standards for the wide variety of design configurations, created by designers, kit manufacturers, and amateur builders." ## Aircraft - Registration: [N164JL](https://openairdocs.org/deregistered/N164JL-2002-11-26), registration cancelled 2002-11-26, S/N 300 (OpenAirDocs) - Reported make and model: Lockamy SONEX - Registry model: [Lockamy Jack L SONEX](https://openairdocs.org/model/lockamy-jack-l-sonex) (registry code 05613S4) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 300 - Engines: Volkswagen Type 4 reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Jack Lockamy - Airworthiness certificate: Special, Experimental (Special) - Departed: OXN, OXNARD, CA - Destination: OXN, Oxnard, CA - Airport: OXR, Oxnard Airport ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 41; injuries: serious; private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim ## Weather - Conditions: Visual (VMC), Day - Wind: 270° at 12 knots - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 72 °F, dew point 57 °F - Altimeter: 29.95 inHg - Observed at: OXR ## 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 20020908024859A](https://openairdocs.org/incident/20020908024859A), Sep 8, 2002: Amtr SONEX, Oxnard, CA, Substantial damage. (-23) On September 8, 2002, approx. 11:36 am pilot jack lockamy departed runway 25 at oxr. At approx. 500 feet AGL over the departure end of the runway Mr.… 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.