# NTSB FTW98LA007: Beech G18S, N9312Y, Crosbyton, TX, October 6, 1997 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Limited investigation · Final report - Date: October 6, 1997, 18:30 local (23:30 UTC) - Place: Crosbyton, TX - Coordinates: 33.640975, -101.229652 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=33.6410&lon=-101.2297&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report February 11, 2000 - Report: Approved by Office Director - NTSB case key (mKey): 20447 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW98LA007 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/20447/pdf - Page: https://openairdocs.org/ntsb/FTW98LA007 ## Probable cause Inadequate maintenance which resulted in diminished carburetor heat effectiveness due to missing alternate air doors. Contributing were conducive carburetor icing weather conditions, low ceilings during the emergency descent, and the lack of suitable terrain for the forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power, cruise - 1 engine - induction air control,alternate air/door - missing (cause) - carburetor heat - diminished (cause) - weather condition - carburetor icing conditions (contributing factor) - weather condition - low ceiling (contributing factor) - Forced landing, emergency descent/landing - terrain condition - rough/uneven - terrain condition - none suitable (contributing factor) ## Analysis While in cruise flight at 9,000 feet MSL, the left engine began to 'run rough and lose power.' The pilot said he interpreted the problem as carburetor icing and applied carburetor heat. With the engine still running rough, the left propeller was feathered and the left engine shut down. Restart attempts were not successful. Unable to maintain altitude, the pilot requested to land at a nearby airport. After descending through IMC weather, the pilot realized that he would not make it to the airport, and executed a forced landing to rough/uneven terrain. Examination of the engines revealed that the alternate air doors were missing on the right and left engine. The hinges for the doors were attached to both carburetors and showed no evidence of distortion or impact damage. The doors were not found at the wreckage site. A missing alternate air door would allow ambient air to enter the carburetor, rendering the carburetor heating system ineffective. According to carburetor icing probability charts, the reported temperature and dew point values would be favorable to the formation of induction system icing. ## Factual narrative On October 6, 1997, at 1830 central daylight time, a Beech G18S airplane, N9312Y, owned and operated by May Air Express of New Boston, Texas, was substantially damaged during a forced landing following a loss of engine power, near Crosbyton, Texas. The airline transport rated pilot, the sole occupant, sustained serious injuries. Instrument meteorological conditions prevailed in the vicinity of the accident and an IFR flight plan was filed for the Title 14 CFR Part 135 air cargo flight. The flight originated from Lubbock Municipal Airport, Lubbock, Texas, at 1730. The pilot reported the following information in the Pilot/Operator Aircraft Accident Report(NTSB Form 6120.1/2) and during an interview with a FAA inspector. He stated that, while in cruise flight at 9,000 feet MSL, the left engine began to "run rough and lose power," which he suspected to be due to "carburetor ice." He further stated that he "deployed the manifold heat" but "encountered mechanical trouble moving the lever all the way down (heat on)." After " a few minutes" the he secured the left engine and feathered the propeller to "let the ice melt." He "repeatedly" attempted to restart the engine, but the propeller "would not unfeather." During the "whole ordeal" the pilot was unable to maintain altitude or a descent rate less than "200 feet per minute," and the aircraft kept buffeting on the edge of a stall. He stated that, after the airplane descended through a scattered cloud layer, he realized that he would not make it to the Crosbyton Airport. Subsequently, he executed a forced landing to grass covered terrain in a canyon about 5 miles northeast of the airport. He reported that the touch down was "hard but smooth [and then the airplane] struck uneven ground." According to recorded transmissions between the pilot and Lubbock Approach Control, the pilot notified the controller at Lubbock Approach that the airplane was experiencing a problem involving "manifold icing," and he would be landing at Crosbyton Municipal Airport, Crosbyton, Texas. Examination of the aircraft by an FAA airworthiness inspector found that the front of the airplane, from the instrument panel forward, was separated from the fuselage. Both engine nacelles were found separated from the wings and the empennage and tail remained intact. He reported that the hinge for the alternate air door on the left engine was attached, but the alternate air door(part number, 18-970011-25) was missing. He stated that the hinge did not appear to be damaged or distorted. The alternate air door was not found in the wreckage. Examination of the right engine revealed that the alternate air door was also missing from its hinge (which was not damaged). According to the FAA airworthiness inspector, a missing alternate air door on the carburetor air box would allow ambient air to enter the carburetor, rendering the carburetor heat system ineffective. At the time of the accident the reported weather conditions at the Lubbock Airport, located 32 nautical miles west of the accident site were; winds from 140 degrees at 15 knots, a scattered cloud layer at 800 feet, a broken cloud layer at 1,600 feet, and an overcast cloud layer at 11,000 feet. The temperature was 64 degrees and the dew point was 63 degrees. According to carburetor icing probability charts, the reported temperature and dew point values would be favorable to the formation of induction system icing. According to the Pilot/Operator Aircraft Accident Report(NTSB form 6120.1/2) the airline transport rated pilot had accumulated a total of 3,222 hours, of which 1,328 hours were in the Beech 18. The pilot had accumulated 650 hours of night flight time, of which 180 hours were in the Beech 18. ## Aircraft - Registration: [N9312Y](https://openairdocs.org/deregistered/N9312Y-2017-04-04), registration cancelled 2017-04-04, S/N BA-550, built 1960 (OpenAirDocs) - Reported make and model: Beech G18S - Registry model: [Beech G18S](https://openairdocs.org/model/beech-g18s) (registry code 1151010) (OpenAirDocs) - Registry engine: [Pratt & Whitney R-985 series](https://openairdocs.org/engine/pratt-whitney-r-985-series) (registry code 52008, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: BA-550 - Airframe hours: 17974 - Engines: P&W R-985 450 horsepower reciprocating - Damage: Substantial damage - Flight: Part 135 - Registered owner: May Air Express Inc. - Airworthiness certificate: Standard, Normal - Last inspection: AAIP, September 10, 1997, 28 hours before - Departed: LBB, LUBBOCK, TX - Destination: DFW, DFW INTNL., TX - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 35; airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 3,222 total, 1,328 in this make and model, 3,048 as pilot in command, 237 in the last 90 days, 76 in the last 30 days, 5 in the last 24 hours ## Weather - Conditions: Instrument (IMC), Dusk - Wind: 140° at 15 knots - Visibility: 10 statute miles - Lowest ceiling: 1,600 ft broken - Temperature: 64 °F, dew point 63 °F - Altimeter: 29.00 inHg - Observed at: LBB, 30 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 19971006045479A](https://openairdocs.org/incident/19971006045479A), Oct 6, 1997: Beech G18S, Crosbyton, TX, Substantial damage. (.4) On October 6, 1997, at 1830 central daylight time, a Beech G18S airplane, N9312Y, owned and operated by may air express of new boston, Texas, was… 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.