# NTSB SEA93LA217: Beech G35, N4641D, Arlington, WA, September 15, 1993 - Type: NTSB accident investigation - Classification: Accident · No injuries · Limited investigation · Final report - Date: September 15, 1993, 14:00 local (21:00 UTC) - Place: Arlington, WA - Coordinates: 48.180767, -121.670417 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=48.1808&lon=-121.6704&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 2 uninjured - Status: Completed, report October 20, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 41782 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA93LA217 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41782/pdf - Page: https://openairdocs.org/ntsb/SEA93LA217 ## Probable cause FRACTURE OF THE LEFT STABILIZER SPAR. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, approach - vfr pattern - downwind - stabilizer - fractured (cause) ## Analysis WHILE ENTERING THE LANDING PATTERN THE PILOT FELT A 'BUMP' FOLLOWED BY A VIBRATION AND FORE AND AFT OSCILLATION OF THE CONTROL COLUMN. AN RPM INCREASE AND THROTTLE/SPEED REDUCTION WAS EFFECTED AND THE VIBRATION CEASED. AN UNEVENTFUL LANDING FOLLOWED. EXAMINATION OF THE AIRCRAFT REVEALED THAT THE LEFT STABILIZER SPAR WAS COMPLETELY FRACTURED THROUGH THE UPPER AND LOWER OUTBOARD BOLTS. METALLURGICAL EXAMINATION REVEALED NO PREEXISTING CRACK AND CHARACTERIZED THE FRACTURE AS TYPICAL OF AN OVERSTRESS SEPARATION. THE RUDDERVATORS WERE WEIGHED AND FOUND TO BE WITHIN BALANCE TOLERANCE LIMITS. ## Factual narrative On September 15, 1993, approximately 1400 hours Pacific daylight time (PDT), a Beech G35 "V" tail Bonanza, N4641D, registered to J. B. Phillips, and being flown by Robert L. Woolverton, a certificated instrument rated private pilot, sustained substantial damage when the left stabilizer main spar separated along a fracture line through several spar attach bolts within the empennage area. The pilot and passenger were uninjured, and the aircraft, which was entering the landing pattern at the Arlington Municipal Airport, Arlington, Washington, at the time of the occurrence, was successfully landed without further damage. Visual meteorological conditions prevailed at the time and no flight plan had been filed. The flight, which was personal in nature, was to have been operated in accordance with the requirements set forth in 14CFR91 and originated at Arlington. The Safety Board was first notified of the occurrence by the insurance adjustor on October 8, 1993. The pilot reported to a Beech representative that while descending into the downwind leg of the traffic pattern at about 170 mph he felt a "bump" similar to what one would expect when encountering their own wake turbulence after a 360 degree constant altitude turn. Immediately thereafter, the airplane began to vibrate with the control column oscillating fore and aft. The pilot reduced power to idle, increased propeller control to high RPM and began to decelerate the aircraft. The vibration ceased soon after and the aircraft was landed without difficulty. Inspection of the aircraft by the Beech representative revealed damage to the aft fuselage and empennage (refer to attached letter). Additionally, the left stabilizer spar was found to be fractured through the upper and lower outboard attach bolt holes. The balance of both the left and right ruddervators was found to be within acceptable limits. Additionally, Beech Service Bulletin 2188 had been applied to the aircraft several years previous to the occurrence. The two sections of spar were sent to the Board's Materials Laboratory Division for examination. There was no evidence of any preexisting fracture and no bending deformation, and the fracture surface was described as "typical of an overstress separation" (refer to attached Metallurgical report). ## Aircraft - Registration: [N4641D](https://openairdocs.org/deregistered/N4641D-2017-03-06), registration cancelled 2017-03-06, S/N D-4810, built 1956 (OpenAirDocs) - Reported make and model: BEECH G35 - Registry model: [Beech G35](https://openairdocs.org/model/beech-g35) (registry code 1151516) (OpenAirDocs) - Registry engine: [Continental E225 series](https://openairdocs.org/engine/continental-e225-series) (registry code 17015, reciprocating) (OpenAirDocs) - Category: Airplane - Serial number: D-4810 - Airframe hours: 4916 - Engines: CONTINENTAL E-225-8 225 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Operator: Philips, J. B. - Registered owner: Philips, J. B. - Airworthiness certificate: Standard, Utility; Standard, Normal - Last inspection: Annual, February 1, 1993 - Destination: S88 ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 54; private; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 1,300 total ## Weather - Conditions: Visual (VMC), Day - Wind: 290° at 8 knots - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 68 °F, dew point 52 °F - Altimeter: 30.00 inHg - Observed at: S88 ## 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 19930915052519A](https://openairdocs.org/incident/19930915052519A), Sep 15, 1993: Beech G35, Arlington, WA, Substantial damage. Felt bump on downwind. Yoke and aircraft vibrated. Too fast slowed late. Landed. Left stabilizer spar fractured. 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.