# NTSB ERA17LA335: Brad J Bates Mosquito XE 285, N926KB, Odessa, FL, September 25, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: September 25, 2017, 17:40 local (21:40 UTC) - Place: Odessa, FL · 9450 Roberts Road. Odessa, FL 33556 - Coordinates: 28.120832, -82.594169 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=28.1208&lon=-82.5942&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-descent: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA/FSDO - NTSB case key (mKey): 96080 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA17LA335 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/96080/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=96080 - Page: https://openairdocs.org/ntsb/ERA17LA335 ## Probable cause A total loss of engine power due to cold seizure of the No.1 piston, which resulted in its failure and a subsequent emergency autorotation and impact with a house’s roof. ## 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 · Damaged/degraded (probable cause); cases with it: [Brad J Bates MOSQUITO XE 285, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=056355D), [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 · Failure (probable cause); cases with it: [Brad J Bates MOSQUITO XE 285, 1 case](https://openairdocs.org/ntsb-findings/01058530/cases.md?model=056355D), [All aircraft, 373 cases](https://openairdocs.org/ntsb-findings/01058530/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-descent: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Brad J Bates MOSQUITO XE 285, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=056355D), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Autorotation: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Brad J Bates MOSQUITO XE 285, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=056355D), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis According to the pilot of the experimental amateur-built helicopter, after departure, the flight was uneventful with no indications of any mechanical problems. After flying around the local area between 800 and 1,000 ft above mean sea level for about 45 minutes, the pilot started to return to the departure site and began a slow descent, after which, he noticed a substantial loss of engine and rotor rpm. He then tried to increase power with no response, so he entered an emergency autorotation and started looking for a landing spot. He aimed to land in an open area, but the helicopter was unable to reach it and impacted a house’s roof. Download and examination of data from the helicopter’s electronic engine monitor indicated that the engine had experienced an overheat event. The overheating was confirmed during a postaccident examination of the helicopter’s engine when it was discovered that the coolant return line, which carried heat away from the engine’s cylinders and was rated for a maximum temperature of 200° F, had melted off its brass connector. Additionally, both the Nos.1 and 2 pistons exhibited scoring on their sides. The No.1 piston’s sides were also fractured, and pieces were missing. Additionally, the No.1 spark plug electrode exhibited evidence of metallic splatter. This evidence indicates that the engine likely experienced cold scoring, which can occur if power is applied before the engine has been brought up to normal operating temperature. When this occurs, it results in the piston heating up and expanding faster than the cylinder, losing clearance between the piston and cylinder, and the piston contacting the sides of the cylinder bore, and seizing. It is likely the No. 1 piston experienced a cold seizure, which resulted in its failure and a subsequent total loss of engine power. ## Factual narrative On September 25, 2017, about 1740 eastern daylight time, an experimental amateur-built, Mosquito XE 285 helicopter, N926KB, was substantially damaged when it was involved in an accident in Odessa, Florida. The pilot sustained minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. According to the pilot, after departure, the flight was uneventful with no indications of any mechanical problems. After flying around the local area between 800 and 1,000 ft above mean sea level for about 45 minutes, the pilot started to return to the departure site and began a slow descent, after which the pilot noticed a substantial loss of engine and rotor rpm. He then tried to increase power with no response, so he immediately entered an autorotation and started looking for a landing spot. He aimed for an open area, but the helicopter was unable to reach it, and impacted a house’s roof. The helicopter’s special airworthiness certificate was issued on April 20, 2017, and at the time of the accident, the helicopter and engine had accrued about 18 total hours of operation. The helicopter was equipped with a liquid-cooled, fuel- and oil-injected, two-cylinder, two-cycle engine, which had aluminum pistons and steel-sleeved cylinders. It was also equipped with an MGL Avionics Stratomaster Velocity engine monitor. Examination of the accident site and the wreckage revealed that the helicopter had come to rest on its left side on the house’s roof. The cockpit was on the forward side of the roof’s peak, and the tailboom, which was still attached but bent, was on the back side of the roof’s peak. The left landing gear skid had penetrated the roof, and two holes were found in the roof that corresponded to the location of the main rotor blade tips. The trailing edge of one of the main rotor blades had a slight kink. Both main rotor blades were attached to the rotor head, and the tail rotor was attached to the tailboom. Control continuity was established to the main and tail rotors. Examination of the engine revealed that it was clean and free of debris and that oil was present in the oil tank. The coolant return line. which carried heat away from the engine’s cylinders and was rated for a maximum temperature of 200°F, was found melted off its brass connector. Metallic spatter was observed on the No.1 cylinder’s spark plug electrode. Scoring was observed on sides of both the Nos. 1 and 2 pistons. Additionally, the sides of the No.1 piston were fractured, and pieces were missing. The tops of both pistons were intact, and oil was present. When the engine monitor was powered up, it showed the last recorded maximum temperatures as follows: the No.1 cylinder exhaust gas temperature was 1,122°F, the No. 2 cylinder exhaust gas temperature was 1,144°F, the cylinder head temperature was 600°F, and the radiator temperature was and 600°F. ## Aircraft - Registration: [N926KB](https://openairdocs.org/deregistered/N926KB-2020-08-19), registration cancelled 2020-08-19, S/N MXE 1306A17B, built 2017 (OpenAirDocs) - Reported make and model: BRAD J BATES MOSQUITO XE 285 (NO SERIES) - Registry model: [Brad J Bates MOSQUITO XE 285](https://openairdocs.org/model/brad-j-bates-mosquito-xe-285) (registry code 056355D) (OpenAirDocs) - Registry engine: [Suzuki INNTEC-800](https://openairdocs.org/engine/suzuki-inntec-800) (registry code 59354, 2 cycle) (OpenAirDocs) - Category: Helicopter, amateur-built - Serial number: MXE 1306A17B - Year built: 2017 - Airframe hours: 17.5 - Engines: Suzuki Inntec 800 85 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, April 20, 2017, 17.5 hours before - Departed: Odessa, FL - Equipment: Handheld GPS ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 51; injuries: minor; private; medical: class 3, with waivers/limitations; last flight review July 6, 2017; seat: single; restraint: 4-point; flight hours: 80 total, 18 in this make and model, 32 as pilot in command, 9 in the last 90 days, 1 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 290° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: 25,000 ft broken - Temperature: 88 °F, dew point 70 °F - Altimeter: 29.82 inHg - Observed at: TPA, 9 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 20170925020899A](https://openairdocs.org/incident/20170925020899A), Sep 25, 2017: Brad J. Bates MOSQUITO XE285, Odessa, FL, Substantial damage. N926KB departed from (10207 lake grove drive, Odessa, FL) for a local flight of about 40-minute, with approximately 10 gallons of 93 octane. When the pilot… ## Docket (5 files) The files NTSB released with the investigation on July 20, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=96080. 16.9 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12317035&FileExtension=pdf&FileName=NTSB%20Form%206120_Redacted-Rel.pdf - Witness statements and interview summaries (item 2, PDF, 9 pages, 6.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12316196&FileExtension=pdf&FileName=Witness%20Statements%20and%20Interview%20Summaries_Redacted-Rel.pdf - Memorandum for record - NTSB engine examination (item 3, PDF, 1 page, 188 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12316509&FileExtension=pdf&FileName=Memorandum%20for%20Record%20-%20NTSB%20Engine%20Examination-Rel.pdf - Photo array (item 4, PDF, 18 pages, 8.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12316876&FileExtension=pdf&FileName=Photo%20Array-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 5, PDF, 1 page, 92 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12316519&FileExtension=pdf&FileName=Wreckage%20Release_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.