# NTSB WPR21LA316: Beech 77, N3873Y, Stanley, NM, August 12, 2021 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: August 12, 2021, 11:00 local (17:00 UTC) - Place: Stanley, NM · Stanley, NM near White Lakes Rd/Hwy 41 - Coordinates: 35.167793, -105.96872 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=35.1678&lon=-105.9687&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA FSDO - NTSB case key (mKey): 103693 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR21LA316 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/103693/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=103693 - Page: https://openairdocs.org/ntsb/WPR21LA316 ## Probable cause A loss of engine performance due to lead fouling of the lower spark plugs, which resulted in an off airport forced landing. ## 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 · Damaged/degraded (probable cause); cases with it: [Beech 77, 1 case](https://openairdocs.org/ntsb-findings/01057421/cases.md?model=1153007), [All aircraft, 38 cases](https://openairdocs.org/ntsb-findings/01057421/cases.md) - [Object/animal/substance: fence/fence post](https://openairdocs.org/ntsb-findings/03022047): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Beech 77, 1 case](https://openairdocs.org/ntsb-findings/03022047/cases.md?model=1153007), [All aircraft, 313 cases](https://openairdocs.org/ntsb-findings/03022047/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Beech 77, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=1153007), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Initial climb: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Beech 77, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=1153007), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) - [Landing: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Beech 77, 9 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1153007), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot departed an airport at an elevation about 5,800 ft mean sea level (msl), and reported that, upon reaching about 6,700 ft msl, the airplane would not continue to climb. The pilot performed a forced landing to a field, during which the right wing impacted a fence post, resulting in substantial damage. Examination of the engine revealed that all lower spark plugs were severely lead fouled. According to the manufacturer, severely lead fouled spark plugs can lead to misfiring, resulting in a degradation of engine performance. It is likely that the fouled spark plugs resulted in a loss of engine performance and the airplane’s subsequent inability to maintain altitude. ## Factual narrative On August 12, 2021, about 1100 mountain daylight time, a Beech 77, N3873Y, was substantially damaged when it was involved in an accident near Stanley, New Mexico. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot departed Double Eagle II Airport (KAEG), Albuquerque, New Mexico, about 1000. The atmospheric conditions at the time of departure resulted in a density altitude of about 8,000 ft. The pilot reported that, during the climb, the airplane maintained a 200 foot per minute (fpm) rate of climb; however, 3 days earlier, under similar atmospheric conditions and airplane loading, the airplane maintained a climb rate of 500 fpm. The pilot further reported that the airplane would not climb higher than 6,700 ft mean sea level, and he decided to maneuver the airplane toward the destination airport. About 300 ft above the ground, as he maneuvered to the southeast to follow a road, the pilot noticed that the terrain was rising and elected to perform a forced landing. Shortly after touchdown, the airplane impacted a cattleguard post and the slid about 200 feet to a stop, resulting in substantial damage to the right wing. Performance calculations for the accident takeoff from the pilots operating handbook indicated that, given a pressure altitude of 5,527 ft, outside air temperature of 24°C, airplane weight of 1,645 lbs, flaps 0°, mixture leaned to maximum rpm, and power at full throttle, the airplane’s rate of climb should have been about 475 fpm. A postaccident examination of the airframe revealed no anomalies or malfunctions. Examination of the engine established mechanical continuity throughout the engine and valve train. The top spark plugs were carbon fouled and displayed black, sooty deposits, while the lower spark plugs were heavily lead fouled, and displayed hard, cinder-like globules of lead around the firing end and cavity. (see figure 1.) According to the pilot, he believed that he had an undetected fouled plug. Figure 1. Top: View of lower spark plugs; Left: Close-up view of no. 1 & 3 spark plugs; Right: View of no. 2 & 4 spark plugs According to Champion Aerospace Aviation Service Manual for spark plugs: Severely fouled spark plugs will operate colder, causing misfires, and will also misfire at higher power because of the conductive nature of the deposits at elevated temperatures. According to the engine logbooks, all spark plugs were cleaned and gapped during the most recent annual inspection about 1 year before the accident. ## Aircraft - Registration: [N3873Y](https://openairdocs.org/deregistered/N3873Y-2023-05-31), registration cancelled 2023-05-31, S/N WA-265, built 1981 (OpenAirDocs) - Reported make and model: BEECH 77 (NO SERIES) - Registry model: [Beech 77](https://openairdocs.org/model/beech-77) (registry code 1153007) (OpenAirDocs) - Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs) - Category: Airplane - Serial number: WA-265 - Year built: 1981 - Airframe hours: 6533 - Engines: LYCOMING O-235 SERIES 115 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Gillett Drew A - Registered owner: Gillett Drew A - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 1, 2020, 146 hours before - Departed: KAEG, Albuquerque, NM - Destination: KBGD, Borger, TX - Airport: AEG, Double Eagle II, runway 04/22, 7,398 × 100 ft, asphalt - Equipment: Handheld GPS, Electronic flight bag or handheld device, ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 71; injuries: none; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: basicmed, without waivers/limitations; seat: left; restraint: lap only; flight hours: 7,000 total, 4,000 in this make and model, 6,900 as pilot in command ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 79 °F, dew point 54 °F - Altimeter: 30.24 inHg - Observed at: KAEG, 41 nm away - METAR: METAR KAEG 121650Z 16003KT 10SM CLR 26/12 A3024= ## 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 20210812020719A](https://openairdocs.org/incident/20210812020719A), Aug 12, 2021: Beech 77, Stanley, NM, Substantial damage. On August 12, 2021, about 1100 MDT, a Beech 77 skipper, N3873Y, [privacy data omitted], was substantially damaged when it was involved in an accident near… ## Docket (8 files) The files NTSB released with the investigation on March 16, 2023, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=103693. 18.5 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12667579&FileExtension=pdf&FileName=6120%20316_Redacted-Rel.pdf - Accident photos (item 2, PDF, 5 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15115466&FileExtension=pdf&FileName=Accident%20Photos-Rel.pdf - NTSB examination notes (item 3, PDF, 8 pages, 896 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15115006&FileExtension=pdf&FileName=Airframe%20and%20Engine%20Examination%20316-Rel.pdf - Spark plug manufacture reference guide (item 4, PDF, 2 pages, 101 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15115551&FileExtension=pdf&FileName=AV6-R-Aug20141%20Pages%208-9-Rel.pdf - Airplane POH performance climb chart (item 5, PDF, 1 page, 304 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15115700&FileExtension=pdf&FileName=beechcraft-skipper-pilot-operating-handbook%20climb%20performance%20chart-Rel.pdf - Email correspondence with pilot (item 6, PDF, 3 pages, 121 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15114923&FileExtension=pdf&FileName=Email%20Correspondence%20with%20pilot_Redacted-Rel.pdf - Logbook record entry (item 7, PDF, 2 pages, 13.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15115024&FileExtension=pdf&FileName=Logbook%20Record%20Entry_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 8, PDF, 2 pages, 134 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=15166942&FileExtension=pdf&FileName=SIGNED%20Release-of-Wreckage-Form%20N3873Y_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.