# NTSB CHI98LA104: Mooney M20C, N6235U, White River, SD, March 10, 1998 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: March 10, 1998, 13:30 local (20:30 UTC) - Place: White River, SD - Coordinates: 43.560726, -100.739341 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=43.5607&lon=-100.7393&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report May 19, 1999 - Report: Approved by Office Director - NTSB case key (mKey): 10837 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CHI98LA104 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/10837/pdf - Page: https://openairdocs.org/ntsb/CHI98LA104 ## Probable cause the pilot's delay in applying carburetor heat. A factor associated with the accident was the low altitude at which the pilot was flying which limited his landing site selections when the loss of power occurred. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - nonmechanical, cruise - fuel system,carburetor - ice (cause) - carburetor heat - delayed, pilot in command (cause) - Forced landing, descent - emergency - altitude - low, pilot in command (contributing factor) - Wheels up landing, landing - flare/touchdown - terrain condition - snow covered - wheels up landing - intentional, pilot in command ## Analysis While cruising at 500 to 1,200 feet agl, the engine began running rough. The pilot adjusted the fuel mixture. Ten minutes later the engine ran rough again at which time the pilot applied carburetor heat. The engine then lost all power. A forced landing was made in a snow covered field. Post accident inspection revealed ice inside the airbox. ## Factual narrative On March 10, 1998, at 1425 mountain standard time (mst), a Mooney M20C, N6235U, was substantially damaged during a forced landing, approximately 4 miles northwest of White River, South Dakota, following a total loss of engine power. The private pilot and one passenger reported no injuries. The personal 14 CFR Part 91 flight was operating on a special VFR flight clearance in instrument meteorological conditions. A VFR flight plan was on file. The flight departed Rapid City, South Dakota, at 1312 mst, with an intend destination of Sioux City, Iowa. According to the pilot's written statement, after receiving a special VFR clearance he departed Rapid City and maintained an altitude of 500 feet to 1,200 feet above the ground as he followed Interstate 90. The pilot reported that at 1415 mst, he adjusted the fuel mixture to correct a slightly rough running engine. He continued to reported that at 1425 mst, the "...engine ran rough for approximately 15 seconds; I pulled carburetor heat and left it on; the engine quit with the propeller windmilling; I switched fuel tanks back to the fullest tank(right)- no change with airspeed and altitude dropping, I searched for a place to land." The pilot also stated in the safety recommendation section that "...better scan of engine of engine instruments, especially manifold pressure regular application of carburetor heat." The pilot said he suspects it was carburetor ice that caused the engine to lose power. A Federal Aviation Administration Principal Maintenance Inspector (PMI), represented the NTSB on-scene. The PMI said the engine examination revealed after the air element was removed, the element did not have snow or ice on it. He then used a light and an inspection mirror to look inside the airbox where he found four pieces of ice lying inside of the airbox. Two pieces were the size of a quarter and two pieces the size of a dime. ## Aircraft - Registration: [N6235U](https://openairdocs.org/deregistered/N6235U-2007-05-02), registration cancelled 2007-05-02, S/N 2075, built 1962 (OpenAirDocs) - Reported make and model: Mooney M20C - Registry model: [Mooney M20C](https://openairdocs.org/model/mooney-m20c) (registry code 5870208) (OpenAirDocs) - Registry engine: [Lycoming O&VO-360 series](https://openairdocs.org/engine/lycoming-o-vo-360-series) (registry code 41514, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: 2075 - Airframe hours: 1744 - Engines: Lycoming O-360-A1D 180 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Registered owner: Rondo Miller - Airworthiness certificate: Standard, Normal - Last inspection: Annual, February 16, 1998, 38 hours before - Departed: RAP, RAPID CITY, SD - Destination: SUX, SIOUX CITY, IA - Flight plan: VFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 38; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 116 total, 34 in this make and model, 50 as pilot in command, 37 in the last 90 days, 34 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Day - Wind: 30° at 12 knots - Visibility: 1.25 statute miles - Lowest ceiling: 2,600 ft overcast - Temperature: 3 °F, dew point -0 °F - Altimeter: 30.00 inHg - Observed at: RAP, 130 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 19980310003179A](https://openairdocs.org/incident/19980310003179A), Mar 10, 1998: Mooney M20C, White River, SD, Substantial damage. Enroute on special VFR clearance due restricted visbilty. Engine lost power. (.4)while cruising at 500 to 1,200 feet AGL, the engine began running rough. The… 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.