# NTSB FTW96LA050: Beech M35, N9886R, Estancia, NM, November 21, 1995 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Limited investigation · Final report - Date: November 21, 1995, 07:56 local (14:56 UTC) - Place: Estancia, NM - Coordinates: 34.760787, -106.060661 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=34.7608&lon=-106.0607&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: Minor injuries - Injuries: 2 minor, 1 uninjured - Status: Completed, report June 22, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 19712 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW96LA050 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/19712/pdf - Page: https://openairdocs.org/ntsb/FTW96LA050 ## Probable cause improper maintenance and inspection of the engine, ingestion of an air intake bypass door into the engine intake, detonation (or preignition), and failure of the #1 and #2 piston and connecting rod assemblies. A factor relating to the accident was: the lack of suitable terrain for a forced landing. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Loss of engine power(total) - mech failure/malf, cruise - maintenance - improper, other maintenance personnel (cause) - maintenance,inspection - improper, other maintenance personnel (cause) - induction air control,alternate air/door - ingested (cause) - misc,engine pre-ignition and/or detonation (cause) - engine assembly,piston - failure (cause) - engine assembly,connecting rod - failure (cause) - Forced landing, emergency descent/landing - In flight collision with object, emergency landing - terrain condition - none suitable (contributing factor) - terrain condition - mountainous/hilly - object - tree(s) ## Analysis While cruising at 9,500 feet MSL, the pilot noticed 'vibrations' accompanied by a 'slight' loss of power. He then 'heard a loud noise,' observed smoke, and the engine lost 'all power.' Subsequently, the airplane collided with trees during a forced landing on wooded/mountainous terrain. Engine examination revealed the following: A hole, 3 inches in diameter, was found adjacent to the #1 cylinder's attachment point on the right side of the crankcase. Debris from the #1 and #2 pistons and the #1 and #2 connecting rods was found throughout the interior of the crankcase. According to an FAA inspector's report, 'Cylinders 1 and 2 evidenced a catastrophic failure similar to that caused by detonation from uneven fuel distribution.' The rear crankcase journals were dry and displayed thermal damage. The interior of the crankcase and rear section of the crankshaft displayed impact damage associated with internal engine component failures. Part of an air intake bypass door from the throttle body air intake was found lodged in the intake port of the #6 cylinder. Examination of the throttle body revealed that a replacement air intake door had been installed, but maintenance records did not reveal service performed on (or a replacement of) the bypass door. ## Factual narrative On November 21, 1995, approximately 0756 mountain standard time, a Beech BE-35, N9886R, registered to, and operated by the pilot, as a Title 14 CFR Part 91 flight was destroyed during a forced landing near Estancia, New Mexico. Visual meteorological conditions prevailed and no flight plan was filed. The private pilot and one passenger received minor injuries. The business flight was en route to Carlsbad, New Mexico, and originated from Albuquerque International Airport, Albuquerque, New Mexico, approximately 30 minutes prior to the accident. The pilot reported that, while cruising at 9,500 feet MSL, he noticed "vibrations", accompanied by a "slight" loss of power. He then elected to return to Albuquerque. He further reported that, during the return flight, the "engine continued to lose power." Subsequently, the pilot "heard a loud noise", observed "white smoke", and the engine lost "all power." During the ensuing forced landing, the airplane descended into a mountainous area covered in mature forest growth, and came to rest upright, in a nose down attitude. A detailed examination of the engine by a FAA airworthiness inspector revealed the following: A hole, 3-inches in diameter, was found adjacent to the number 1 cylinder's attachment point on the right side of the crankcase. The #1 and #2 cylinders could not be removed from the crankcase. Cylinders #3 through #6 displayed scoring in the barrels. Debris from the #1 and #2 pistons (which were destroyed) was found throughout the interior of the crankcase when the crankcase was opened. Additionally, debris from the #1 and #2 connecting rods (which were destroyed) was found inside the crankcase. The remainder of the connecting rods were intact and were free to rotate on the crankshaft. The rear crankshaft journals were dry and displayed thermal damage. The interior of both crankcase halves, and the rear section of the crankshaft, displayed impact damage associated with numerous internal engine component failures. Part of an air intake bypass door from the throttle body air intake was found lodged in the intake port of the #6 cylinder. Further examination of this door, revealed that, the rivet holes on the door corresponded to the rivet holes in the throttle body hinge. Examination of the throttle body revealed that a replacement air intake bypass door had been installed. A review of the maintenance records did not reveal service performed or a replacement of the bypass door. ## Aircraft - Registration: [N9886R](https://openairdocs.org/deregistered/N9886R-2017-06-15), registration cancelled 2017-06-15, S/N D-6457, built 1960 (OpenAirDocs) - Reported make and model: Beech M35 - Registry model: [Beech M35](https://openairdocs.org/model/beech-m35) (registry code 1151526) (OpenAirDocs) - Registry engine: [Continental I0-470 series](https://openairdocs.org/engine/continental-i0-470-series) (registry code 17027, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: D-6457 - Airframe hours: 5888 - Engines: Continental IO-470-C 250 horsepower reciprocating - Damage: Substantial damage - Flight: Business, Part 91 - Registered owner: Jerry C. Tankersley - Airworthiness certificate: Standard, Normal - Last inspection: Annual, July 2, 1995, 32 hours before - Departed: ABQ, ALBUQUERQUE, NM - Destination: CNM, CARLSBAD, NM ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 61; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 2,513 total, 2,113 in this make and model ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 60 statute miles - Lowest ceiling: none - Altimeter: 30.00 inHg ## 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 19951121037869A](https://openairdocs.org/incident/19951121037869A), Nov 21, 1995: Beech M35, Estancia, NM, Destroyed. Vibration power loss. Made 180 smoke and engine quit. Crashed rough terrain. Bypass door in intake. Engine blew up. 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.