# NTSB WPR17LA187: Cessna 310I, N8170M, Salt Lake City, UT, August 24, 2017 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: August 24, 2017, 14:00 local (20:00 UTC) - Place: Salt Lake City, UT - Coordinates: 40.595832, -111.98833 - Nearby events: https://openairdocs.org/map.md?lat=40.5958&lon=-111.9883&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: 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: Western Pacific Region - Parties: Continental Motors Group, Textron Aviation, FAA-FSDO - NTSB case key (mKey): 95888 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR17LA187 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/95888/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=95888 - Page: https://openairdocs.org/ntsb/WPR17LA187 ## Probable cause A loss of engine power for reasons that could not be determined based on the available information. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant](https://openairdocs.org/ntsb-findings/01057100): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Cessna 310I, 1 case](https://openairdocs.org/ntsb-findings/01057100/cases.md?model=2074224), [All aircraft, 198 cases](https://openairdocs.org/ntsb-findings/01057100/cases.md) - [Not determined](https://openairdocs.org/ntsb-findings/05000000): Not determined › Not determined · Unknown/Not determined (probable cause); cases with it: [Cessna 310I, 4 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md?model=2074224), [All aircraft, 2,247 cases](https://openairdocs.org/ntsb-findings/05000000/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Cessna 310I, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=2074224), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [Cessna 310I, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=2074224), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) - [Emergency descent: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Cessna 310I, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=2074224), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) ## Analysis The pilot reported that, during engine start and run up, the left engine shut down twice when the throttle was reduced to idle, and during the engine run-up magneto checks, the engines ran rough with greater than normal losses in rpm. The pilot advanced the throttles and leaned the mixtures to both engines to “clear” what he thought was “carbon buildup on the sparkplugs” and the engines subsequently ran smoothly at idle. The pilot departed, and during the initial climb, noticed that the airplane did not accelerate as normal. The pilot reduced the angle of attack to aid in acceleration and noticed that both engines indicated fluctuations in power, fuel flow, and rpm. He confirmed that the propeller and throttle levers were full forward, and he placed the auxiliary fuel pump to “high.” The airplane continued to decelerate and began to yaw to the left. The pilot banked right and feathered the left propeller, but the airplane continued to descend, and the pilot reduced the mixture controls to idle-cutoff. The airplane impacted two power poles and the ground before skidding to a stop adjacent to a building. A postaccident fire ensued. Examination of the engines revealed dark and sooty deposits on the sparkplug electrodes, consistent with a rich fuel/air mixture ratio. Additionally, the left engine tachometer generator cannon plug was separated and undamaged. It is possible that this plug disconnected during the takeoff and would have resulted in a tachometer indication of a loss of left engine power. It is likely that the left engine fuel flow was not properly adjusted by maintenance personnel when the engine was installed earlier the month of the accident, which created an overly rich fuel-air mixture and resulted in the repeated loss of left engine power during ground operations; however, the reason for the loss of power during the takeoff and the airplane's inability to gain altitude/airspeed during the initial climb could not be determined based on the available information. ## Factual narrative On August 24, 2017, about 1400 mountain daylight time, a Cessna 310I airplane, N8170M, was substantially damaged when it was involved in an accident near Salt Lake City, Utah. The airline transport pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 aerial photography flight. The pilot reported that, after starting both engines, neither engine ran smoothly at idle power, and the left engine shut down when the throttle was brought to the idle position, but easily restarted. The pilot stated that both engines ran smoothly slightly above an idle power setting. The fuel mixture was leaned for taxi and runup, and exhaust gas temperatures (EGTs) were higher than usual. During the engine runup, the left engine again lost power when the throttle was reduced to idle power, and the pilot again restarted the engine. The propellers produced normal rpm loss when cycled, but the engines ran rougher than expected during the magneto checks, with a loss of about 200 rpm. The pilot advanced the throttles and leaned the mixtures to both engines to clear “suspected carbon buildup on the sparkplugs.” Upon completion of this procedure, both engines ran smoothly at idle power, and a subsequent magneto check produced normal rpm loss. During the initial climb after takeoff, the pilot retracted the landing gear and noticed that the airplane did not accelerate as normal. The pilot reduced the angle of attack to aid in acceleration and noticed that both engines indicated fluctuations in power, fuel flow, and rpm. He confirmed that the propeller and throttle levers were full forward, and he placed the auxiliary fuel pump to “high.” The airplane continued to decelerate and began to yaw to the left. The pilot banked right and feathered the left propeller, but the airplane continued to descend, and the pilot reduced the mixture controls to idle-cutoff. The airplane impacted two power poles and the ground before skidding to a stop adjacent to a building. A postaccident fire ensued. The wreckage was relocated to a secure facility for further examination. The propellers separated from the engines during the accident sequence. The upper engine cowlings were removed and the interior surfaces of both the upper and lower cowling halves were dirty. The engines exterior surfaces were clean and undamaged. The spark plugs were removed from both engines; some of the electrodes displayed sooty deposits and the others were dark in color. The left engine’s tachometer generator was undamaged, and the cannon plug was not attached to the tachometer drive on the engine. The cannon plug and attachment fitting were undamaged. Both engine-driven fuel pumps were removed, and their drive couplings were undamaged. The fuel pumps were undamaged, and their drive shafts rotated freely by hand. Examination of the engines revealed no evidence of preexisting malfunctions or failures that would have precluded normal operation. Each engine fuel systemwas equipped with an electric fuel boost pump controlled by switches in the cockpit. Integrated into each pump electrical circuit was a pressure switch. The cockpit switches had three positions, LOW, OFF, and ON. With the switch in the LOW position, the pump operated at a reduced speed. With the cockpit switch in the ON position, the pump operated at low speed unless the pressure switch sensed a loss of fuel pressure, upon which the electric pump operated at full speed. In 1988, the aircraft manufacturer released Service Bulletin MEB88-3, "Auxiliary Fuel Pump Wiring Modification." The compliance requirement was listed as "Mandatory: Shall be accomplished within the next 100 hours of operation, or no later than the next annual inspection, or during an equivalent inspection for airplanes utilizing the Cessna Progressive Care Inspection Program, whichever occurs first." The Service Bulletin called for the removal of the pressure switches and reconfiguring the cockpit switches and wiring so that the cockpit switches directly controlled the operation of the electric fuel pumps in both LOW and HIGH modes. The cockpit switches were to be relabeled, LOW, OFF, and HIGH. The fuel pump switches in the accident airplane indicated that the middle position was labeled OFF and the upper position was labeled ON. Both switches were found in the OFF position. Additionally, the pressure switches were still installed and connected to the fuel pump wiring. Testing determined that the left engine's pressure switch was stuck in the "pressure" position. The right fuel selector valve handle was found between the "Right" and "Off" positions. The right fuel selector valve was found in the "Off" position. The left fuel selector valve handle was found in the "Left" position. The alternate air door connection on the right engine was excessively worn. Maintenance documentation revealed that both engines were installed in August 2017. The engines had about 16 hours of operation since their overhaul and installation. According to the airplane's Owner’s Manual, the “Before Take-off” procedure included placing the auxiliary fuel pump switches in the “ON” position. The manual stated that twin-engine climb performance at 5,000 ft mean sea level (msl), at 41°F and at maximum gross weight (5,100 lbs), was 1,220 ft per minute (fpm), and 1,650 fpm at 4,300 lbs. Single-engine climb performance at 5,000 ft msl, 41°F, and maximum gross weight was 155 fpm. The rate of climb at that altitude and temperature and a gross weight of 4,300 lbs was 325 fpm. ## Aircraft - Registration: [N8170M](https://openairdocs.org/deregistered/N8170M-2020-12-11), registration cancelled 2020-12-11, S/N 310I0170, built 1964 (OpenAirDocs) - Reported make and model: CESSNA 310I (I) - Registry model: [Cessna 310I](https://openairdocs.org/model/cessna-310i) (registry code 2074224) (OpenAirDocs) - Registry engine: [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series) (registry code 17027, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 310I0170 - Year built: 1964 - Airframe hours: 4802 - Engines: CONT MOTOR I0-470-U SERIES 260 horsepower reciprocating; CONT MOTOR I0-470-U SERIES 260 horsepower reciprocating - Damage: Substantial damage - Fire: On-Ground - Flight: Aerial observation, Part 91 - Airworthiness certificate: Standard, Normal - Last inspection: Annual, August 9, 2017, 16 hours before - Departed: U42, SALT LAKE CITY, UT - Destination: U42, SALT LAKE CITY, UT - Airport: U42, South Valley Rgnl, runway 16, 5,860 × 100 ft, asphalt - Equipment: Electronic flight bag or handheld device, Stall warning system ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 26; injuries: minor; airline transport, commercial; airplane ratings: multi-engine land, single-engine sea, multi-engine sea; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review August 15, 2016; seat: left; restraint: lap only; flight hours: 2,073 total, 1,080 in this make and model, 1,523 as pilot in command, 94 in the last 90 days, 12 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 340° at 11 knots - Visibility: 10 statute miles - Temperature: 90 °F, dew point 45 °F - Altimeter: 30.01 inHg - Observed at: KSLC, 11 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 20170824016559A](https://openairdocs.org/incident/20170824016559A), Aug 24, 2017: Cessna 310I, West Jordan, UT, Destroyed. 1. Aircraft was leaking oil and fuel at a significant rate overnight. 2. Personnel brought the excessive leaking to the pilot?s attention. 3. Pilot claimed the… ## Docket (18 files) The files NTSB released with the investigation on March 11, 2021, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=95888. 25.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 3.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11920772&FileExtension=pdf&FileName=17-0903%20NTSB%20Form%206120%20-%20N8170M%20_Redacted-Rel.pdf - NTSB engine examination summary (item 2, PDF, 6 pages, 1.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=12041190&FileExtension=pdf&FileName=WPR17FA187%20Wreckage%20Examination%20Summary-Rel.pdf - Textron aviation-technical report (item 3, PDF, 8 pages, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921827&FileExtension=pdf&FileName=Tech%20Report%20310I0170_Redacted-Rel.pdf - Fuel receipt (item 4, PDF, 3 pages, 973 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921090&FileExtension=pdf&FileName=Fuel%20Receipts_Redacted-Rel.pdf - Letter-apex aviation (item 5, PDF, 2 pages, 557 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11920358&FileExtension=pdf&FileName=Apex%20Letter_Redacted-Rel.pdf - Email-pacific Continental engines, inc. (item 6, PDF, 1 page, 50 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921553&FileExtension=pdf&FileName=Email-Pacific%20Continental%20Engines%20N8170M%20Logbook%20Release_Redacted-Rel.pdf - MEB88-3 airworthiness directive (item 7, PDF, 1 page, 90 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921634&FileExtension=pdf&FileName=MEB88-3%20AD_Redacted-Rel.pdf - Auxiliary fuel pump wiring modification (item 8, PDF, 24 pages, 1.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921242&FileExtension=pdf&FileName=SK310-104B-Rel.pdf - Operators manual-performance charts (item 9, PDF, 1 page, 60 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921563&FileExtension=pdf&FileName=Pages%20from%20310I%201964%20D848-13%20OM-Rel.pdf - Airframe logbooks-excerpts (item 10, PDF, 5 pages, 1.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11920970&FileExtension=pdf&FileName=Pages%20from%20Airframe%20Log_Redacted-Rel.pdf - Left engine logbook-excerpts (item 11, PDF, 6 pages, 764 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921699&FileExtension=pdf&FileName=Pages%20from%20L%C2%A0engine%C2%A0log%C2%A0_Redacted-Rel.pdf - Right engine logbook-excerpts (item 12, PDF, 6 pages, 1.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11937077&FileExtension=pdf&FileName=Pages%20from%20R%C2%A0Engine%C2%A0Log_Redacted-Rel.pdf - Operators manual-checklists (item 13, PDF, 4 pages, 76 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11920980&FileExtension=pdf&FileName=Pages%20from%20310I%201964%20D848-13%20OM%20Checklists-Rel.pdf - Statement of party representatives to NTSB investigation-pce (item 14, PDF, 1 page, 160 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921252&FileExtension=pdf&FileName=PCE%20Party%20Form_Redacted-Rel.pdf - Statement of party representatives to NTSB investigation-textron aviation (item 15, PDF, 1 page, 686 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921110&FileExtension=pdf&FileName=Textron%20Aviation%20Party%20Form_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 16, PDF, 1 page, 417 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11937417&FileExtension=pdf&FileName=Wreckage%20Release%20Scanned_Redacted-Rel.pdf - Photo array-onsite (item 17, PDF, 19 pages, 5.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921406&FileExtension=pdf&FileName=Onsite%20Photo%20Array-Rel.pdf - Photo array-followup examination (item 18, PDF, 9 pages, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=11921232&FileExtension=pdf&FileName=Followup%20Examination%20Photo%20Array-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.