# NTSB LAX98LA182: Cessna 150M, N704ZA, Livermore, CA, June 4, 1998 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: June 4, 1998, 15:00 local (22:00 UTC) - Place: Livermore, CA - Coordinates: 37.680969, -121.75061 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=37.6810&lon=-121.7506&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor - Status: Completed, report March 30, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 30107 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX98LA182 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/30107/pdf - Page: https://openairdocs.org/ntsb/LAX98LA182 ## Probable cause The missing nut/cotter pin on the throttle attachment assembly which resulted in the pilot's inability to control engine power, and the hidden obstruction (hole) in the landing area. A factor was the high vegetation. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - mech failure/malf, cruise - miscellaneous,bolt/nut/fastener/clamp/spring - missing (cause) - throttle/power lever,linkage - disconnected - Nose over, landing - roll - terrain condition - hidden obstruction(s) (cause) - terrain condition - high vegetation (contributing factor) ## Analysis After performing air work, the instructor and student were returning to base. The instructor noted a loss of rpm's from 2,300 to 1,100. He took over the aircraft controls from the student and attempted to correct the problem. The instructor noted that the rpm's remained constant at 1,100. He conducted the emergency checklist and informed the tower of the situation. The instructor then landed the aircraft in an open field of high grass during which the aircraft came to rest inverted after the nose wheel struck a hole. The aircraft was examined on-scene and it was noted that the bolt was in place, but that the nut and cotter pin were missing from the carburetor throttle attachment assembly. It was also noted that the aircraft had flown approximately 15 hours since the last annual inspection and maintenance had been performed. ## Factual narrative On June 4, 1998, at 1500 hours Pacific daylight time, a Cessna 150M, N704ZA, experienced a loss of engine power and made an emergency landing in an open field 3 miles west of the Livermore, California, airport. The aircraft, operated by Flying Vikings under 14 CFR Part 91, sustained substantial damage. The commercial rated flight instructor pilot and student pilot, the sole occupants, received minor injuries. Visual meteorological conditions existed for the instructional flight and no flight plan was filed. In an interview with a Federal Aviation Administration (FAA) inspector from the Oakland, California, Flight Standards District Office, the pilot reported that they were in level flight at 2,500 feet above ground level (agl) when the engine rpm dropped. They attempted to land at the Livermore airport, but had to make an emergency landing in an open field. The aircraft came to rest inverted. In the instructor pilot's written statement, he reported that after performing air work they were returning to base when they experienced a loss of rpm's from 2,300 to 1,100. He stated that he took over the controls and noted that the "power level [did] not respond to any of my applications." The instructor stated that the power setting remained constant at 1,100 rpm's. He completed the emergency checklist and informed the tower of their situation and landed in the open field. The instructor reported that on the landing rollout the nose wheel hit a hole in the ground and the aircraft flipped over. The instructor reported that due to high vegetation he was unable to see the rough terrain before landing. The aircraft was examined by the FAA on-scene. The FAA inspector noted that the bolt was in place, but that the nut and cotter pin were missing from the carburetor throttle attachment assembly. According to the FAA, the aircraft had flown approximately 10-15 hours since the last annual inspection and maintenance had been performed. The Army National Guard was conducting maneuvers at the time of the accident and rescued the flight instructor and student pilot. They also extinguished a postimpact engine fire. ## Aircraft - Registration: [N704ZA](https://openairdocs.org/deregistered/N704ZA-1998-09-21), registration cancelled 1998-09-21, S/N 15078992 (OpenAirDocs) - Reported make and model: Cessna 150M - Registry model: [Cessna 150M](https://openairdocs.org/model/cessna-150m) (registry code 2071830) (OpenAirDocs) - Category: Airplane - Serial number: 15078992 - Airframe hours: 6500 - Engines: Continental O-200 100 horsepower reciprocating - Damage: Substantial damage - Flight: Instructional, Part 91 - Operator: Flying Vikings - Registered owner: Michael Adams - Airworthiness certificate: Standard, Normal; Standard, Utility - Last inspection: Annual, May 8, 1998, 15 hours before - Departed: HWD ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 27; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: right; flight hours: 1,700 total, 600 in this make and model, 1,495 as pilot in command, 150 in the last 90 days, 40 in the last 30 days, 3 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 260° at 13 knots - Visibility: 10 statute miles - Lowest ceiling: 3,500 ft broken - Temperature: 64 °F, dew point 52 °F - Altimeter: 30.00 inHg - Observed at: LVK, 3 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 19980604012339A](https://openairdocs.org/incident/19980604012339A), Jun 4, 1998: Cessna 150M, Livermore, CA, Substantial damage. Lost rpms. Tried for hwd but landed off airport. Nosed over. Post impact engine fire. Throttle disconnected. (From .4) after performing air work, the… 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.