# NTSB CEN18LA189: M-Squared Sprint 1000, N138ZX, Gurdon, AR, May 22, 2018 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: May 21, 2018, 19:15 local (May 22, 2018, 00:15 UTC) - Place: Gurdon, AR - Coordinates: 33.923053, -93.157218 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.9231&lon=-93.1572&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Central Region - Parties: FAA FSDO - NTSB case key (mKey): 97304 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN18LA189 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/97304/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=97304 - Page: https://openairdocs.org/ntsb/CEN18LA189 ## Probable cause Inadequate engine maintenance, which resulted in the failure of the MAG piston ring and the subsequent total loss of engine power due to a piston seizure. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Failure (probable cause); cases with it: [M-Squared SPRINT 1000, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=059025M), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Engine (reciprocating): recip eng cyl section](https://openairdocs.org/ntsb-findings/01058530): Aircraft › Aircraft power plant · Not serviced/maintained (probable cause); cases with it: [M-Squared SPRINT 1000, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=059025M), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) - [Maintenance: scheduled/routine maintenance](https://openairdocs.org/ntsb-findings/02062010): Personnel issues › Task performance · Owner/builder (probable cause); cases with it: [M-Squared SPRINT 1000, 1 case](https://openairdocs.org/ntsb-findings/02062010/cases.md?model=059025M), [All aircraft, 320 cases](https://openairdocs.org/ntsb-findings/02062010/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [M-Squared SPRINT 1000, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=059025M), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [M-Squared SPRINT 1000, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=059025M), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The pilot reported that he and a passenger had just departed on a local, personal flight when the engine “suddenly stopped.” Shortly thereafter, the engine seized, and the airplane began to descend rapidly. The pilot deployed the airplane's ballistic parachute about 200 ft above ground level, and the airplane then landed hard in a residential area, which resulted in substantial damage to the wings and fuselage. The pilot recalled that, during the takeoff and climb, the instruments showed no unusual indications and that the engine made no unusual sounds. Examination of the engine revealed that the top of the MAG piston ring had failed, which resulted in damage to the MAG piston and cylinder walls. Both rubber PTO and MAG carburetor intake sockets were worn and cracked. Complete engine records were not available, and no record was found indicating that the engine had been overhauled during its 23 years of operation. The engine manufacturer recommended that the engine should be overhauled every 300 hours or 5 years, whichever occurred first, and that the rubber carburetor intake sockets should be replaced every 5 years or as signatures of deterioration were detected. Cracked rubber carburetor intake sockets can result in a lean mixture and lead to a piston seizure. The inadequate maintenance of the engine likely led to the failure of the MAG piston ring and the subsequent loss of all engine power due to a piston seizure. ## Factual narrative On May 21, 2018, about 1915 central daylight time, an M-Squared Sprint 1000 light-sport airplane, N138ZX, was substantially damaged when it was involved in an accident near Gurdon, Arkansas. The pilot and passenger were seriously injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported to the Federal Aviation Administration (FAA) inspector that the airplane had just departed from runway 26 at Gurdon Lowe Field. When the airplane was about 800 ft above ground level (agl), "the engine suddenly stopped." As the pilot looked for a suitable landing site, the "engine seized up", and the airplane began to descend rapidly. The pilot deployed the airplane's ballistic parachute about 200 ft agl. The airplane descended and landing hard in a residential area. The airplane's wings and fuselage were substantially damaged. The pilot recalled that during the takeoff and climb there were no unusual indications from the instruments, nor any unusual sounds from the engine. The engine was examined by the FAA inspector with technical assistance from the engine manufacturer. Examination of the engine revealed that the top of the MAG piston ring had failed resulting in damage to the MAG piston and cylinder walls. The examination also noted vertical scoring on the PTO cylinder, and significant vertical scoring on the MAG cylinder. In addition, both rubber PTO and MAG carburetor intake sockets were worn and cracked. Complete engine records were not available and there was no record that showed that the engine had been overhauled during its 23 years of operation. The manufacturer recommends an engine overhaul be performed every 300 hour or 5 years, whichever occurs first. The rubber carburetor intake sockets should be replaced every 5 years or when signatures of deterioration are detected. ## Aircraft - Registration: [N138ZX](https://openairdocs.org/aircraft/N138ZX), registered now, S/N 000582DT, built 2006 (OpenAirDocs) - Reported make and model: M-SQUARED AIRCRAFT SPRINT 1000 (NO SERIES) - Registry model: [M-Squared SPRINT 1000](https://openairdocs.org/model/m-squared-sprint-1000) (registry code 05904V1) (OpenAirDocs) - Registry engine: [Rotax 618](https://openairdocs.org/engine/rotax-618) (registry code 55578, 2 cycle) (OpenAirDocs) - Category: Airplane - Serial number: 000582DT - Year built: 2006 - Airframe hours: 285.7 - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, September 14, 2017 - Departed: 5M8, Gurdon, AR - Destination: 5M8, Gurdon, AR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; injuries: serious; sport pilot; airplane ratings: single-engine land; medical: sport pilot, unknown; seat: front; restraint: 4-point ## Weather - Conditions: Visual (VMC), Day - Wind: 90° at 3 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 82 °F, dew point 72 °F - Altimeter: 29.95 inHg - Observed at: KHOT, 23 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 20180521005729A](https://openairdocs.org/incident/20180521005729A), May 21, 2018: M-Squared Aircraft SPRINT 1000, Gurdon, AR, Substantial damage. On may 21, 2018 at approximately 1915 CDT, N138ZX a M-Squared, sprint 1000 experimental operating as light sport aircraft, registered to stephen c. pennington… ## Docket (5 files) The files NTSB released with the investigation on October 9, 2020, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=97304. 1.5 MB in all. - NTSB form 6120 not received (item 1, PDF, 1 page, 46 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9647935&FileExtension=pdf&FileName=Form%206120%20not%20returned-Rel.pdf - Photo (item 2, PDF, 1 page, 857 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9640933&FileExtension=pdf&FileName=Photo-Rel.pdf - Engine field notes (item 3, PDF, 5 pages, 134 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9640262&FileExtension=pdf&FileName=2018-029%20M-Squared%20Field%20Notes-Rel.pdf - Pilot's statement (item 4, PDF, 1 page, 318 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9640852&FileExtension=pdf&FileName=My_Scan_2018_06_12_11_46_30_978_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation (item 5, PDF, 1 page, 127 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=9650577&FileExtension=pdf&FileName=DOC051220-05122020135157_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.