# NTSB WPR10LA465: Mooney M20C, N6090Q, Visalia, CA, September 21, 2010 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 21, 2010, 09:40 local (16:40 UTC) - Place: Visalia, CA - Coordinates: 36.318611, -119.392776 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=36.3186&lon=-119.3928&mi=10 - Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping) - Defining event: [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report December 13, 2011 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 77356 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR10LA465 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77356/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77356 - Page: https://openairdocs.org/ntsb/WPR10LA465 ## Probable cause A partial loss of engine power during takeoff, which resulted from the failure of the spark plug retention mechanism. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Ignition system: spark plugs/igniters](https://openairdocs.org/ntsb-findings/01057421): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [Mooney M20C, 2 cases](https://openairdocs.org/ntsb-findings/01057421/cases.md?model=5870208), [All aircraft, 38 cases](https://openairdocs.org/ntsb-findings/01057421/cases.md) - [Personnel issues](https://openairdocs.org/ntsb-findings/02040000): Personnel issues › Action/decision · Pilot; cases with it: [Mooney M20C, 1 case](https://openairdocs.org/ntsb-findings/02040000/cases.md?model=5870208), [All aircraft, 56 cases](https://openairdocs.org/ntsb-findings/02040000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Takeoff: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340); cases with it: [Mooney M20C, 3 cases](https://openairdocs.org/ntsb-events/340/sequence.md?model=5870208), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Takeoff: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Mooney M20C, 6 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=5870208), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Mooney M20C, 21 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=5870208), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing-flare/touchdown: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Mooney M20C, 39 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=5870208), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot applied full engine power, took off, and climbed to about 300 feet above the runway. The engine suddenly lost partial power, and the pilot elected to return to the airport for a forced landing. The airplane’s altitude was insufficient to complete the turn, and the airplane impacted the ground adjacent to the departure runway, substantially damaging the right wing. An examination of the engine revealed that the retention mechanism for the bottom No. 3 spark plug failed and the spark plug had blown out of its cylinder. Its failure appeared related to excessive wear and the loosening over time of the Heli-Coil insert. According to the Federal Aviation Administration, evidence of the Heli-Coil’s loosening would not, necessarily, have been apparent to a mechanic during routine maintenance. ## Factual narrative On September 21, 2010, about 0940 Pacific daylight time, a Mooney M20C, N6090Q, experienced a partial loss of engine power during takeoff from Visalia Municipal Airport, Visalia, California. During a low altitude course reversal turn back to the runway, the airplane impacted the ground hard and was substantially damaged. The commercial pilot owned, operated, and maintained the airplane. He was not injured during the personal flight. Visual meteorological conditions prevailed, and the flight was performed under the provisions of 14 Code of Federal Regulations Part 91. No flight plan was filed. The flight was originating at the time of the accident. The pilot reported that, in preparation for takeoff, he had performed an engine run-up, and no anomalies were noted. Thereafter, he applied full engine power and commenced taking off. At 300 feet above the runway he heard a loud pop noise, and the engine’s rpm decreased to 1,500. Unable to maintain flight, the pilot initiated a course reversal turn for a forced landing back on the airport. However, the airplane’s altitude was insufficient to complete the turn, and he impacted the ground adjacent to the departure runway. The impact was sufficiently hard to activate the emergency locator transmitter, break off the nose gear, and bend the outboard 6 feet of the right wing. Federal Aviation Administration (FAA) personnel subsequently examined the airplane’s engine. The FAA reported that a bottom spark plug of the Lycoming engine's number three cylinder had blown out of its cylinder. FAA personnel additionally reported that the spark plug had been installed in the cylinder hole with a Heli-Coil insert, which surrounds the plug's threads in the cylinder. The blown out spark plug was found, and it appeared to have failed due to wear from repeated insertions and removals, while the Heli-Coil gradually loosened. FAA personnel further opined that the spark plug had not been loose in the cylinder. Rather, the Heli-Coil showed evidence of loosening over time. Evidence of the Heli-Coil’s loosening would not, necessarily, have been apparent to the mechanic during routine maintenance, according to the FAA. The engine had over 1,600 hours of total time since its last major overhaul. The number three cylinder had not been replaced since its 1987 overhaul, according to maintenance records. ## Aircraft - Registration: [N6090Q](https://openairdocs.org/deregistered/N6090Q-2011-06-18), registration cancelled 2011-06-18, S/N 3260, built 1965 (OpenAirDocs) - Reported make and model: MOONEY M20C - Registry model: [Mooney M20C](https://openairdocs.org/model/mooney-m20c) (registry code 5870208) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 3260 - Airframe hours: 6718 - Engines: LYCOMING O-360A1D 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, April 30, 2010, 13 hours before - Departed: VIS, Visalia Municipal, CA - Destination: VIS, Visalia Municipal, CA - Airport: VIS, Visalia Municipal, runway 30, 6,559 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 63; injuries: none; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review August 28, 2009; seat: left; flight hours: 2,674 total, 1,600 in this make and model, 2,294 as pilot in command, 10 in the last 90 days, 4 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 66 °F, dew point 55 °F - Altimeter: 29.77 inHg - Observed at: VIS ## 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 20100921044529A](https://openairdocs.org/incident/20100921044529A), Sep 21, 2010: Mooney M20C, Visalia, CA, Substantial damage. 0940, 21 September, 2010 Visalia, CA. During takeoff just after rotation, the pilot heard a 'bang' and immediately lost power. The engine RPM dropped to 1500.… ## Docket (6 files) The files NTSB released with the investigation on November 2, 2011, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77356. 2.6 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 355 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40337205&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF - Email FAA-NTSB (Extract) (item 2, .PDF, 51 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356871&FileExtension=.PDF&FileName=Email%20FAA-NTSB%20(Extract)-Redacted.PDF - Aircraft & Engine Logs (Extract) (item 3, .PDF, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356872&FileExtension=.PDF&FileName=Aircraft%20%26%20Engine%20Logs%20(Extract)-Redacted.PDF - Avco Lycoming Service Instruction No. 1043A (item 4, .PDF, 44 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356864&FileExtension=.PDF&FileName=Avco%20Lycoming%20Service%20Instruction%20No.%201043A-Master.PDF - Photo 1. Heli-Coil & Spark Plug, FAA Photo (item 5, .PDF, 162 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356873&FileExtension=.PDF&FileName=Photo%201.%20Heli-Coil%20%26%20Spark%20Plug,%20FAA%20Photo-Master.PDF - Photo 2. Plug hole in cylinder #3 (item 6, .PDF, 199 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40356874&FileExtension=.PDF&FileName=Photo%202.%20Plug%20hole%20in%20cylinder%20%233-Master.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.