# NTSB ERA15LA311: Thomas A Siminski Zenith CH 750, N1750Z, Allentown, PA, August 14, 2015 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: August 14, 2015, 11:10 local (15:10 UTC) - Place: Allentown, PA - Coordinates: 40.570278, -75.488334 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.5703&lon=-75.4883&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: Serious injuries - Injuries: 1 serious - Status: Completed, report November 19, 2015 - Report: Approved by Office Director - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 91785 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA15LA311 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/91785/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=91785 - Page: https://openairdocs.org/ntsb/ERA15LA311 ## Probable cause A partial loss of engine power due to the No. 1 spark plug being liberated from the cylinder head due to the stripped threads in the cylinder head. Contributing to the accident was the pilot’s decision to attempt to return to the airport while at a low altitude. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip engine power section](https://openairdocs.org/ntsb-findings/01058520): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-findings/01058520/cases.md?model=05631LG), [All aircraft, 233 cases](https://openairdocs.org/ntsb-findings/01058520/cases.md) - [Ignition system: spark plugs/igniters](https://openairdocs.org/ntsb-findings/01057421): Aircraft › Aircraft power plant · Not specified (probable cause); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-findings/01057421/cases.md?model=05631LG), [All aircraft, 38 cases](https://openairdocs.org/ntsb-findings/01057421/cases.md) - [Info processing/decision: decision making/judgment](https://openairdocs.org/ntsb-findings/02041520): Personnel issues › Action/decision · Pilot (probable cause); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-findings/02041520/cases.md?model=05631LG), [All aircraft, 3,098 cases](https://openairdocs.org/ntsb-findings/02041520/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); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=05631LG), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05631LG), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Emergency descent: Abrupt maneuver](https://openairdocs.org/ntsb-events/270); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/270/sequence.md?model=05631LG), [All aircraft, 346 cases](https://openairdocs.org/ntsb-events/270/sequence.md) - [Emergency descent: Aerodynamic stall/spin](https://openairdocs.org/ntsb-events/241); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/241/sequence.md?model=05631LG), [All aircraft, 1,529 cases](https://openairdocs.org/ntsb-events/241/sequence.md) - [Uncontrolled descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Thomas A Siminski ZENITH CH 750, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=05631LG), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The pilot reported that, after takeoff, the airplane's engine lost partial power about 100 ft above ground level and that he then attempted to return to the airport. The pilot further stated that "the engine would not keep me flying and the airplane just fell into the forest." During the on-scene examination, the No. 1 spark plug was found missing from the cylinder head but still attached to the ignition lead. The threads were stripped out of the cylinder head. It is likely that the No. 1 spark plug was liberated from the cylinder head due to the stripped threads, which led to the partial loss of engine power. ## Factual narrative On August 14, 2015, about 1110 eastern daylight time, an experimental, amateur-built Zenith CH750, N1750Z, was substantially damaged when it impacted trees and terrain shortly after takeoff at Queen City Airport (XLL), Allentown, Pennsylvania. The private pilot was seriously injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight, which was operated under the provisions of Title 14 Code of Federal Regulations Part 91. The flight was originating at the time of the accident. The pilot reported that after takeoff from runway 25, the engine lost partial power about 100 feet above ground level. The pilot further stated that the engine would not keep him flying. He attempted to return back to runway 7, but the airplane impacted trees and a creek bed, resulting in substantial damage to the airframe. According to the pilot and Federal Aviation Administration (FAA) records, he held a private pilot certificate with a rating for airplane single-engine land. The pilot reported 328 hours of total flight experience. The wreckage was examined at the scene by a FAA inspector. The inspector reported that the airplane was submerged, nose down, in about 2 feet of water. About 10 gallons of fuel were recovered from the airplane's fuel tanks. The airplane's airworthiness certificate was issued in 2012, and since that time it had accumulated 75 total flight hours. The inspector found the number 1 spark plug missing from the cylinder head but still attached to the ignition lead. The pilot's son took several pictures of the spark plug, ignition lead and cylinder head. He verified that the threads were stripped out of the cylinder head, and the threads on the spark plug looked to be in good condition. ## Aircraft - Registration: [N1750Z](https://openairdocs.org/deregistered/N1750Z-2018-07-06), registration cancelled 2018-07-06, S/N 75-7859, built 2012 (OpenAirDocs) - Reported make and model: THOMAS A SIMINSKI ZENITH CH 750 - Registry model: [Thomas A Siminski ZENITH CH 750](https://openairdocs.org/model/thomas-a-siminski-zenith-ch-750) (registry code 05631LG) (OpenAirDocs) - Registry engine: [Corvair GO-140](https://openairdocs.org/engine/corvair-go-140) (registry code 18001, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 75-7859 - Year built: 2012 - Airframe hours: 72 - Engines: Chevrolet GO-140 100 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Siminski Thomas A - Registered owner: Siminski Thomas A - Airworthiness certificate: None - Last inspection: Annual, September 3, 2014 - Departed: XLL, ALLENTOWN, PA - Destination: XLL, ALLENTOWN, PA - Airport: XLL, Allentown Queen City Muni, runway 25, 3,949 × 75 ft, asphalt - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 68; injuries: serious; sport pilot; airplane ratings: single-engine land; medical: unknown; seat: left; restraint: 3-point; flight hours: 327.7 total, 74 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: 250° at 6 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 63 °F - Altimeter: 30.18 inHg - Observed at: KABE, 5 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 20150814014509A](https://openairdocs.org/incident/20150814014509A), Aug 14, 2015: Thomas A Siminski ZENITH CH 750, Allentown, PA, Substantial damage. Aircraft departed Allentown queen city (xll) runway 25 on a personal flight approximately 1100 local. The engine lost power approximately 100 ft AGL, the pilot… ## Docket (4 files) The files NTSB released with the investigation on October 23, 2015, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=91785. 2.2 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433098&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - FAA Inspector's Statement (item 2, .PDF, 57 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433099&FileExtension=.PDF&FileName=FAA%20Inspector%27s%20Statement-Master.PDF - Memorandum for Record – Telephone Interview, Pilot (item 3, .PDF, 52 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433100&FileExtension=.PDF&FileName=Memorandum%20for%20Record%20%E2%80%93%20Telephone%20Interview,%20Pilot%20-Master.PDF - Photo Array (item 4, .PDF, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40433101&FileExtension=.PDF&FileName=Photo%20Array-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.