# NTSB WPR21LA171: Consolidated Aeronautics Lake LA-4-200, N2989P, Twentynine Palms, CA, April 21, 2021 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: April 21, 2021, 14:10 local (21:10 UTC) - Place: Twentynine Palms, CA - Coordinates: 34.136313, -115.98359 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.1363&lon=-115.9836&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Kelly Aero, Lycoming, Federal Aviation Administration - NTSB case key (mKey): 102960 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA171 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/102960/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=102960 - Page: https://openairdocs.org/ntsb/WPR21LA171 ## Probable cause A partial loss of engine power due to inadequate ignition from cracked spark plugs and a failed magneto. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Ignition system: magneto/distributor](https://openairdocs.org/ntsb-findings/01057414): Aircraft › Aircraft power plant · Fatigue/wear/corrosion (probable cause); cases with it: [Consolidated Aeronautics LAKE LA-4-200, 1 case](https://openairdocs.org/ntsb-findings/01057414/cases.md?model=2400108), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/01057414/cases.md) - [Ignition system: spark plugs/igniters](https://openairdocs.org/ntsb-findings/01057421): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [Consolidated Aeronautics LAKE LA-4-200, 1 case](https://openairdocs.org/ntsb-findings/01057421/cases.md?model=2400108), [All aircraft, 38 cases](https://openairdocs.org/ntsb-findings/01057421/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Consolidated Aeronautics LAKE LA-4-200, 4 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=2400108), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) ## Analysis The pilot had recently purchased the airplane and was transporting it to his home airport. During the cross-country flight, the pilot stopped to refuel the airplane. During departure, the airplane climbed to an altitude of about 200 ft above ground level, at which point the engine lost partial power and was unable to maintain altitude. The pilot elected to perform an emergency off-airport landing, and the airplane touched down on desert terrain. During the landing, the airplane collided with a sign and nosed over, coming to rest inverted. The airplane had undergone a pre-buy and an annual inspection about 10 flight hours before the accident. The pilot stated that, on the day before the accident, he flight tested the airplane, during which time the manual turbocharger went into overboost for “a second” before he pulled the power back. A postaccident examination revealed that several ceramic cores of the spark plugs were cracked. The combustion chambers were free from deposits, consistent with a preignition or detonation event. It is unknown if the overboost event that the pilot described resulted in this damage. The magnetos, while still installed on the engine, did not produce a consistent spark, and their timing could not be determined. The magnetos were then removed from the engine. The right magneto was functionally tested and operated normally. The left magneto capacitor lead insulation had previously been cut, exposing the center conductor wire, consistent with improper assembly. The contact point tungsten faces were both corroded and exhibited an oxide crust on the external surfaces of the tungsten. A functional test, revealed the left magneto would not produce spark at different rpms. The left magneto was likely not operating during the accident takeoff, which, along with the cracked spark plugs, would have resulted in a partial loss of engine power. ## Factual narrative History of Flight On April 21, 2021, about 1410 Pacific daylight time, a Consolidated Aeronautics Lake LA-4-200, N2989P, sustained substantial damage when it was involved in an accident near Twentynine Palms, California. The pilot, the sole occupant, sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot stated that he had recently purchased the airplane and had undergone training in the airplane make and model. The purpose of the flight was for the pilot to transport the airplane from the seller’s location in Novato, California, to his home airport in Texas. On the morning of the accident, the pilot departed about 0800, made a fuel stop, and departed again before landing in Twentynine Palms about 1330. He filled the fuel tanks to their maximum capacity and began the departure from runway 26. The airplane climbed to about 200 ft above ground level (agl), at which point the engine lost partial power and was unable to maintain altitude. The engine began to vibrate, and the pilot could hear a “loud chatter noise” from the engine area. He noted that the manifold pressure gauge appeared normal and that the digital tachometer displayed fluctuating rpm. The pilot verified that the auxiliary boost pump was selected to the “on” position and retracted the flaps to maximize the time that the airplane would be able to stay airborne. The pilot further stated that he was unable to maintain altitude and that, after determining that the airplane would not be able to return to the departure airport, he elected to make an emergency landing on a road. As the airplane approached the road, the pilot observed power lines and decided to have the airplane touch down on the adjacent desert terrain. During the landing, the airplane collided with a sign, and the airplane nosed over, coming to rest inverted. Aircraft Information The Lake LA-4-200 is a mid-wing single-engine amphibian airplane powered by a fuel-injected four-cylinder piston engine. The engine, which is mounted on a vertical pylon above the fuselage, drives the two-bladed constant-speed pusher propeller. In 1983, the accident airplane was outfitted with a Rayjay turbocharger under a supplemental type certificate. The pilot stated that, during the day before the accident, he flight tested the airplane, and the manual turbocharger went into overboost for “a second” before he pulled the power back. The airplane’s logbooks indicated that the engine was the original engine installed at the time of manufacture. The last annual inspection, which was also a pre-buy inspection, occurred on March 1, 2021, at a total time of 1,727 hours and about 10 hours before the accident. Records indicated that the last 500-hour magneto inspection was in May 2002 at a total aircraft time of 1,339 hours; the capacitor on the right magneto was replaced at a total time of 1,493 hours. Wreckage and Impact Information A postaccident examination of the engine foundthat the crankshaft could be rotated by hand using the propeller. The crankshaft was easy to rotate in both directions. A “thumb” compression test was performed on all cylinders and strong pressure was felt trying to escape at the upper spark plug bores. The entire valve train operated properly. Mechanical continuity was established throughout the rotating group, valve train, and accessory section during hand rotation of the crankshaft. Clean, uncontaminated oil was observed at all four rocker box areas. Removal of the spark plugs revealed that they were oily and that several had cracked ceramic cores. The cylinders were removed, and the pistons were free from deposits. The magnetos did not produce a consistent spark; as a result, their timing could not be determined. The magnetos were then tested at Kelly Aero in Montgomery, Alabama. Both magnetos were in good condition with no oil or dust contamination beyond normal wear. The distributor gears of both magnetos were free from damage. The right magneto was functionally tested, and it operated within test parameters, producing consistent spark at different rpm. The left magneto failed to produce a spark at different rpm; the impulse coupling engaged between 75 and150 rpm and then disengaged above 450 rpm. Disassembly of the left magneto revealed that capacitor lead insulation had previously been cut, which exposed the center conductor wire. The contact point tungsten faces were corroded and exhibited an oxide crust on the external surfaces of the tungsten (see the figure below). When the operational capacitor of the right magneto was replaced with the left magneto’s capacitor, consistent spark was produced at different rpm. Additionally, after replacing the corroded contact points of the left magneto with those from the right magneto, the left magneto also produced consistent spark at different rpm. Figure 1. Magneto points. Additional Information Lycoming Engines issued Mandatory Service Bulletin (SB) 592 regarding the corrective actions to be taken after an overboost event. For engines configured similarly to the accident engine, the SB states, in pertinent part, to inspect spark plugs for a ceramic core nose with a cracked or crazed surface. It is unknown if the overboost event that the pilot described made the accident airplane engine subject to the actions in the SB (because no information was available regarding the pressure exceedance and exact duration of the event). ## Aircraft - Registration: [N2989P](https://openairdocs.org/deregistered/N2989P-2025-05-31), registration cancelled 2025-05-31, S/N 954, built 1979 (OpenAirDocs) - Reported make and model: CONSOLIDATED AERONAUTICS INC. LAKE LA-4-200 - Registry model: [Consolidated Aeronautics LAKE LA-4-200](https://openairdocs.org/model/consolidated-aeronautics-lake-la-4-200) (registry code 2400108) (OpenAirDocs) - Registry engine: [Lycoming I0360 SER A&C](https://openairdocs.org/engine/lycoming-i0360-ser-a-c) (registry code 41511, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 954 - Year built: 1979 - Airframe hours: 1737 - Engines: Lycoming IO-360-A1B 200 hp reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, March 1, 2021, 10 hours before - Destination: KGEU, Glendale, AZ - Flight plan: VFR - Airport: TNP, Twentynine Palms - Equipment: Auto-pilot, Handheld GPS, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 67; injuries: minor; private; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: basicmed, without waivers/limitations; last flight review October 4, 2020; seat: left; restraint: 4-point; flight hours: 3,963 total, 14 in this make and model, 3,730 as pilot in command, 43 in the last 90 days ## Weather - Conditions: Visual (VMC), Day - Wind: 280° at 8 knots, gusting 19 - Visibility: 9 statute miles - Lowest ceiling: none - Temperature: 75 °F, dew point 28 °F - Altimeter: 29.78 inHg - Observed at: KNXP, 13 nm away - METAR: KNXP 212056Z AUTO 28008G19KT 9SM CLR 24/M02 A2978 RMK AO2 SLP051 T02441022 57014 ## 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 20210421006169A](https://openairdocs.org/incident/20210421006169A), Apr 21, 2021: Consolidated Aeronautics Inc. LAKE LA-4-200, Twenty Nine Pal, CA, Substantial damage. N2989P departed knta airport. Airplane climed to about 200 feet above AGL at which aircraft had partial loss of powerand was unable to maintain altitude.… ## Docket (8 files) The files NTSB released with the investigation on June 8, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=102960. 28.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 8 pages, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15438052&FileExtension=pdf&FileName=Z%20-%20Attachment%2001-%206120_Redacted-Rel.pdf - Investigation supplemental material (item 2, PDF, 10 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15543181&FileExtension=pdf&FileName=Z%20-%20Attachment%2002-%20Investigative%20Suplemental%20Material-Rel.pdf - Kelly aero magneto report (item 3, PDF, 5 pages, 557 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15437184&FileExtension=pdf&FileName=Z%20-%20Attachment%2003-%20Kelly%20Magneto%20Report-Rel.pdf - Record of conversation (item 4, PDF, 1 page, 98 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15438273&FileExtension=pdf&FileName=Z%20-%20Attachment%2002%20-%20Record%20of%20Conversations-Rel.pdf - Lycoming overboost service bulletin (item 5, PDF, 4 pages, 221 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15438263&FileExtension=pdf&FileName=Z%20-%20Attachment%2004-%20Lycoming%20Service%20Bulletin%20on%20Overboost-Rel.pdf - Last annual, pre buy, and logbook excerpts (item 6, PDF, 24 pages, 20.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15438229&FileExtension=pdf&FileName=Z%20-%20Attachment%2008-%20Last%20Annual,%20Pre%20Buy%20and%20Logbook%20Excerpts%20REDACTED-Rel.pdf - Statement of party representatives to NTSB investigation - kelly aero (item 7, PDF, 1 page, 4.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15438021&FileExtension=pdf&FileName=Z%20-%20Attachment%2006%20-%20Party%20Form%20Kelly%20Aero_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation - Lycoming (item 8, PDF, 1 page, 195 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15437665&FileExtension=pdf&FileName=Z%20-%20Attachment%2007%20-%20Party%20Form%20Lycoming_Redacted-Rel.pdf 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.