# NTSB DEN99LA054: Cessna 320D, N4127T, Broomfield, CO, March 16, 1999 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 15, 1999, 21:46 local (Mar 16, 1999, 04:46 UTC) - Place: Broomfield, CO - Coordinates: 39.939819, -105.059204 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=39.9398&lon=-105.0592&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report October 13, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 45918 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN99LA054 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/45918/pdf - Page: https://openairdocs.org/ntsb/DEN99LA054 ## Probable cause A partial loss of power on the left engine for undetermined reasons. A factor was the pilot's failure to maintain directional control of the aircraft during landing flare/touchdown. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(partial) - nonmechanical, cruise - normal - 1 engine - loss,partial (cause) - reason for occurrence undetermined (cause) - Loss of control - in flight, landing - flare/touchdown - directional control - not maintained, pilot in command (contributing factor) - On ground/water encounter with terrain/water, landing - roll - terrain condition - grass ## Analysis The airplane was north of the airport at 8,000 feet in bound for landing when she turned on the fuel boost pumps and switched from the auxiliary to the main tanks following a momentary surge. Minutes later, the left engine began to surge again. She was able to substantially restore power to the left engine. During approach to landing, the power on the left engine began to surge again, followed by a partial loss of power. As she flared for landing, the aircraft veered to the left and departed the runway into the grass. Based on the pilot's fuel calculations, the aircraft should have had 53.2 gallons of fuel remaining when she landed. The day after the accident, fuel was found in the right main fuel tank; however, the left tank was compromised and the presence of fuel could not be verified. Following the accident, the left engine was run in a test cell. The engine operated up to the maximum available power, and no discrepancies were observed. The turbocharger was also examined, and no abnormalities were found. ## Factual narrative On March 15, 1999, at 2146 mountain standard time, a Cessna 320D, N4127T, operated by Star West Aviation of Evanston, Wyoming, was substantially damaged when it collided with terrain following a partial loss of power on the left engine during final approach to landing at Jefferson County (Jeffco) Airport, Broomfield, Colorado. The commercial pilot, the sole occupant aboard, was not injured. The aircraft was being operated as a non-scheduled domestic cargo flight under Title 14 CFR Part 135, and an IFR flight plan had been filed. The flight originated from Cheyenne, Wyoming, approximately 51 minutes before the accident. Visual meteorological conditions prevailed. According to the pilot, while 25 nautical miles north of Jeffco Airport and level at 8,000 feet, there was a momentary surge of power on the left engine. She turned on the fuel boost pumps and switched from the auxiliary to the main tanks. Approximately one to two minutes later, the left engine began to surge again and went to near zero thrust; however, the rpm still had some indication of power. She verified that the loss of power was on the left engine. She then checked to make sure that the fuel pumps were still on HIGH and that the fuel selectors were in the detent position on the main tanks. She was level at 7,500 feet and on a direct course for the airport when the power was substantially restored, and she returned power to the right engine to stabilize the yawing. She received clearance to land on runway 29R with a right base entry. While approximately four miles from the airport, the power on the left engine began to surge again. While two miles from final approach, the left engine again lost power. The aircraft began rolling and yawing with full right rudder and the left wing raised. The pilot never declared an emergency, and stated that she did not feather the propeller because the engine continued to produce partial thrust. As the aircraft crossed the runway threshold, she reduced the throttles, but the nose continued to yaw toward the left engine with full right rudder applied. As she flared for landing, the aircraft veered to the left. She stated that she had neither the altitude nor the airspeed to correct the situation before touching down. The aircraft departed the runway to the left, and came to rest approximately 75 feet off the runway into the grass. The left landing gear was separated from the aircraft, the left and right propeller blades were bent, and the left wing spar was broken. The total fuel capacity in the Cessna 320D is 140 gallons; 50 gallons in the each of the main tanks, and 20 gallons in the auxiliary tanks. According to an airport employee, he "topped off" N4127T with 79.3 gallons of fuel prior to the aircraft's departure from Evanston-Uinta County Burns Field Airport, the airplane's home base. The pilot's route of flight was from Evanston to Riverton, then to Casper, Cheyenne, and lastly to her final destination of Broomfield, Colorado. The total time en route was 2 hours and 50 minutes. Calculating an average fuel burn of 31 gallons per hour, the aircraft should have had 53.2 gallons of fuel remaining upon landing at Jeffco. The day following the accident, fuel was found in the right main fuel tank; however, the left wing spar had been broken and the left tank was compromised during the landing sequence. The presence of fuel in the left main fuel tank could not be verified. On March 30, 1999, the left engine, without the turbocharger installed, was run in a test cell at the facilities of Firewall Forward in Fort Collins, Colorado. The engine operated up to the maximum available power, and no discrepancies were observed. A flow check was performed on the fuel injectors lines, and the flow on each nozzle appeared evenly distributed. The turbocharger was examined on July 14, 1999, at AlliedSignal Aerospace's test facilities in Torrence, California. No abnormalities were found. ## Aircraft - Registration: [N4127T](https://openairdocs.org/deregistered/N4127T-2001-10-04), registration cancelled 2001-10-04, S/N 320D0027, built 1965 (OpenAirDocs) - Reported make and model: Cessna 320D - Registry model: [Cessna 320D](https://openairdocs.org/model/cessna-320d) (registry code 2074512) (OpenAirDocs) - Registry engine: [Continental TSIO-520 series](https://openairdocs.org/engine/continental-tsio-520-series) (registry code 17040, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 320D0027 - Airframe hours: 5188 - Engines: Continental TSIO-520-BB 285 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Operator: Star West Aviation - Registered owner: Spur Aircraft Rental - Airworthiness certificate: Standard, Normal - Last inspection: 100 hour, March 14, 1999, 10 hours before - Departed: CYS, CHEYENNE, WY - Destination: BJC - Flight plan: IFR - Airport: BJC, Jeffco Airport, runway 29R, 9,000 × 100 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 34; flight instructor, commercial; airplane ratings: multi-engine land, single-engine sea, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 1,537 total, 234 in this make and model, 1,413 as pilot in command, 272 in the last 90 days, 80 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Night/dark - Wind: 260° at 10 knots - Visibility: 30 statute miles - Lowest ceiling: none - Temperature: 52 °F, dew point 18 °F - Altimeter: 29.00 inHg - Observed at: BJC ## 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 19990315002489A](https://openairdocs.org/incident/19990315002489A), Mar 15, 1999: Cessna 320D, Denver, CO, Substantial damage. (-23) According to the pilot, while about 20 miles north of jefferson county airport, she switched the fuel selectors from the auxiliary tanks to the main… 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.