# NTSB WPR17LA046: Softex Invest V-24L, N710XP, Paradise, MT, January 3, 2017 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: January 3, 2017, 09:30 local (16:30 UTC) - Place: Paradise, MT - Coordinates: 47.398334, -114.816947 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.3983&lon=-114.8169&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Defining event: [Enroute-cruise: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) - Highest injury: Serious injuries - Injuries: 2 serious - Status: Completed, report June 25, 2019 - Report: Approved by Office Director - NTSB office: Western Pacific Region - Parties: FAA-FSDO, Lycoming - NTSB case key (mKey): 94555 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR17LA046 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/94555/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=94555 - Page: https://openairdocs.org/ntsb/WPR17LA046 ## Probable cause A partial loss of power during cruise flight for reasons that could not be determined because postaccident examination of the engines did not reveal evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=056345E), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) - [Terrain: sloped/uneven terrain](https://openairdocs.org/ntsb-findings/03021017): Environmental issues › Physical environment · Contributed to outcome; cases with it: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-findings/03021017/cases.md?model=056345E), [All aircraft, 270 cases](https://openairdocs.org/ntsb-findings/03021017/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Enroute-cruise: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-events/000/sequence.md?model=056345E), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) - [Enroute-cruise: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=056345E), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Enroute-cruise: Attempted remediation/recovery](https://openairdocs.org/ntsb-events/060); cases with it: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-events/060/sequence.md?model=056345E), [All aircraft, 1,422 cases](https://openairdocs.org/ntsb-events/060/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=056345E), [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: [Softex Invest V-24L, 1 case](https://openairdocs.org/ntsb-events/470/sequence.md?model=056345E), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md) ## Analysis The airline transport pilot reported that, about 30 minutes after departure for the cross-country personal flight in visual conditions, he noticed a vibration. He checked the engine instruments and did not see anything abnormal. However, he noted that the airplane's airspeed and altitude were rapidly decreasing, so he applied full power to both engines, but the airplane continued to descend, indicative of a partial loss of engine power, so he chose to conduct a forced, off-airport landing in a field. The airplane impacted terrain and then came to rest after impacting a ditch. Postaccident examinations of the airframe and engines revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. The reason for the vibration and the subsequent partial loss of power could not be determined. ## Factual narrative The 4-seat low-wing, retractable-gear, multi-engine pusher experimental airplane, serial number 14-03-05, was manufactured in 2014. According to the maintenance logbooks, the airplane received its first and only condition inspection on June 30, 2016. The left engine was a Lycoming, fuel-injected YIO-320-D1B engine, serial number EL-6259-55E. Total time recorded on the engine at the time of the condition inspection was 62.5 hours. The right engine was a Lycoming, fuel-injected YIO-320-D1B engine, serial number EL-6260-55E. Total time recorded on the engine at the time of the condition inspection was 62.5 hours. Fueling records at Northstar Jet, Missoula, Montana, established that the airplane was last fueled on September 2, 2016 with the addition of 24.7 gallons of aviation fuel. The general manager reported that each morning, before aircraft fueling, a fuel sample is tested from the facility fuel sump. On the morning of September 2, 2016, the fuel sample retained received a rating of "1A", meaning clear and bright and water-free. On January 3, 2017, about 0930 mountain standard time, an experimental amateur-built Softex Investment LLC V-24L airplane, N710XP, collided with terrain during an off-airport landing near Paradise, Montana. The airline transport pilot and passenger were seriously injured. The airplane sustained substantial damage. The airplane was registered to Summit International American and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91 as a personal flight. Visual meteorological conditions prevailed, and no flight plan had been filed. The cross-country flight originated from Missoula, Montana, about 0830 and was destined for Seattle, Washington. The pilot reported that the purpose of the flight was to return the airplane to its home base in Seattle. The day before the flight, the pilot checked the airplane as it had been in a heated hangar for about 10 to 14 days. The pilot started both engines and conducted checks of all the systems including the operation of the propellers. All was normal, and the airplane was put back in the hangar. The next day, the pilot again checked the airplane and did an engine run-up and all systems showed normal. After departure and about 25 to 30 minutes into cruise flight, the airplane was about 1,500 to 1,800 ft above ground level when a vibration developed. The pilot did not see anything abnormal with the engine instruments. He noted that the airspeed was rapidly decreasing along with a loss of altitude, so he applied maximum power to both engines. The airplane continued to descend, and he decided to perform an emergency forced landing in an open area of a railroad yard. An automated surface weather observation at Mullan Pass VOR/DME (MLP), Mullan Pass, Idaho (elevation 6,074 ft msl, 34 miles west of the accident site) was issued 23 minutes after the accident. It indicated wind from 130° at 7 knots, 10 miles or greater visibility, with an overcast ceilingat 5,500 ft, temperature at -17°C, dew point -21°C, and an altimeter setting of 29.96 inches of mercury. An automated surface weather observation at Missoula International Airport (MSO), Missoula, Montana (elevation 3,204 ft msl, 41 miles southeast of the accident site) was issued 23 minutes after the accident. It indicated wind from 110° at 9 knots, 10 miles or greater visibility, few clouds at 6,500 ft, with an overcast ceiling at 9,000 ft, temperature at -14°C, dew point -19°C, and an altimeter setting of 30.26 inches of mercury. The wreckage came to rest at the end of a snow-covered field after impacting a ditch. The landing gear appeared to be in the retracted position. The path of the airplane could be determined by tire marks in the snow. The airplane remained relatively intact, with all four corners of the airplane present at the wreckage site. The empennage separated from the fuselage near the trailing edge of the wings. The left wingtip separated after impacting the ditch. The right-wing spar was damaged near the right wing, which separated from the wing. The left engine remained attached to the left wing. The three propeller blades on each engine were fractured and separated about midspan. Flight control continuity of both ailerons was established to the wing separation point and from the wing separation points on the fuselage to the yoke. Rudder and elevator control continuity was established from the rudder and elevator to the empennage separation point and from the empennage separation point to the rudder pedals and yoke, respectively. The fuel selector valves within the cockpit were in the off positions. The throttle arm, mixture arm, carburetor heat arm, and governor arm followed control movement, and moved freely from stop to stop. The crankshaft rotated freely in both engines and the valves moved approximately the same amount of lift in firing order. Thumb compression was obtained on all cylinders in firing order. All center electrodes of all the spark plugs were circular and clean with no mechanical deformation. The spark plugs were connected to their respective ignition leads and were grounded. The magnetos were manually rotated on the left engine, and both magnetos produced sparks at all plugs except the top spark plug in cylinder No. 2 and the bottom spark plug in cylinder No. 1. The magnetos on the right engine were also rotated, and both magnetos produced sparks at all plugs. Both engine fuel filters were disassembled. A pale blue fluid was inside both filters that smelled similar, but slightly different than 100LL aviation fuel, and contained "sand-like" debris. The same "sand-like" debris remained within the fuel filter container after the fluid was drained. A sample of the fluid was retained for further examination, but the fluid was unable to be tested due to the small quantity. The overall effect and or correlation of the trace amounts of debris in the fuel system and engine performance could not be determined. ## Aircraft - Registration: [N710XP](https://openairdocs.org/deregistered/N710XP-2019-09-06), registration cancelled 2019-09-06, S/N 14-03-05, built 2014 (OpenAirDocs) - Reported make and model: SOFTEX INVEST LLC V-24L (NO SERIES) - Registry model: [Softex Invest V-24L](https://openairdocs.org/model/softex-invest-v-24l) (registry code 056345E) (OpenAirDocs) - Registry engine: [Lycoming YIO-320 SERIE](https://openairdocs.org/engine/lycoming-yio-320-serie) (registry code 42417, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 14-03-05 - Year built: 2014 - Airframe hours: 85.5 - Engines: Lycoming YIO-320-D1B 160 horsepower reciprocating; Lycoming YIO-320-D1B 160 horsepower reciprocating - Damage: Substantial damage - Flight: Ferry, Part 91 - Operator: Summit International American Ltd - Registered owner: Summit International American Ltd - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Annual, June 30, 2016 - Departed: MSO, MISSOULA, MT - Destination: Paradise, MT - Equipment: Electronic multifunction display, Auto-pilot, Angle of attack indicator, Airframe parachute, Stall warning system, Satellite tracking device, Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: serious; airline transport; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review October 17, 2016; seat: left; restraint: 4-point; flight hours: 19,946 total, 20 in this make and model, 8,724 as pilot in command, 145 in the last 90 days, 48 in the last 30 days ## Weather - Conditions: Visual (VMC), Day - Wind: 150° at 8 knots, gusting 15 - Visibility: 10 statute miles - Lowest ceiling: 5,500 ft overcast - Temperature: -0 °F, dew point -8 °F - Altimeter: 29.94 inHg - Icing: Unknown - Observed at: KMLP, 34 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 20170103000149A](https://openairdocs.org/incident/20170103000149A), Jan 3, 2017: Softex Invest LLC V-24L, Paradise, MT, Substantial damage. Pilot and passenger stated a significant vibration developed in flight. At full power the aircraft could not maintain altitude even at approach speed. Pilot… ## Docket (15 files) The files NTSB released with the investigation on April 18, 2019, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=94555. 8.9 MB in all. - Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 4.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472012&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Master.PDF - Record of Conversation - General manager Northstar Jet (item 2, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472013&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20General%20manager%20Northstar%20Jet-Master.PDF - Record of Conversation - Lycoming (item 3, .PDF, 68 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472014&FileExtension=.PDF&FileName=Record%20of%20Conversation%20-%20Lycoming-Master.PDF - Oil Analysis (item 4, .PDF, 39 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472015&FileExtension=.PDF&FileName=Oil%20Analysis-Master.PDF - NTSB Exam Report (item 5, .PDF, 8 photos, 1.4 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472016&FileExtension=.PDF&FileName=NTSB%20Exam%20Report-Master.PDF - Aircraft Logbook (item 6, .PDF, 443 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472017&FileExtension=.PDF&FileName=Aircraft%20Logbook-Master.PDF - Left Engine Propeller Logbook (item 7, .PDF, 340 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472018&FileExtension=.PDF&FileName=Left%20Engine%20Propeller%20Logbook-Master.PDF - Right Engine Propeller Logbook (item 8, .PDF, 489 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472019&FileExtension=.PDF&FileName=Right%20Engine%20Propeller%20Logbook-Master.PDF - Left Engine Logbook (item 9, .PDF, 373 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472020&FileExtension=.PDF&FileName=Left%20Engine%20Logbook-Master.PDF - Right Engine Logbook (item 10, .PDF, 429 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472021&FileExtension=.PDF&FileName=Right%20Engine%20Logbook-Master.PDF - NBAAI Comments (item 11, .PDF, 241 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472022&FileExtension=.PDF&FileName=NBAAI%20Comments-Master.PDF - Statement of Party Representatives to NTSB Investigation (item 12, .PDF, 128 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472023&FileExtension=.PDF&FileName=Statement%20of%20Party%20Representatives%20to%20NTSB%20Investigation-Master.PDF - Fuel Receipts - Northstar Jet (item 13, .PDF, 49 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472024&FileExtension=.PDF&FileName=Fuel%20Receipts%20-%20Northstar%20Jet-Master.PDF - Evidence Control Form (item 14, .PDF, 79 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472025&FileExtension=.PDF&FileName=Evidence%20Control%20Form-Master.PDF - Photos (item 15, .PDF, 6 photos, 779 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40472026&FileExtension=.PDF&FileName=Photos-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.