# NTSB SEA91FA261: Beech 35, N3081V, Walla Walla, WA, January 16, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: January 16, 1991, 14:00 local (22:00 UTC)
- Place: Walla Walla, WA
- Coordinates: 46.109821, -118.299484 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=46.1098&lon=-118.2995&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report March 9, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 41343
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA91FA261
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41343/pdf
- Page: https://openairdocs.org/ntsb/SEA91FA261

## Probable cause

IMPROPER STATIC BALANCE OF THE RUDDERVATORS FOLLOWING REBUILDING/REPAINTING, WHICH RESULTED IN EMPENNAGE FLUTTER. IMPROPER INSTALLATION OF THE TRIM TABS AND AN ENCOUNTER WITH TURBULENCE WERE RELATED FACTORS.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, descent - normal
  - maintenance,rebuild/remanufacture - improper, other maintenance personnel (contributing factor)
  - flight control,rudder tab - improper (contributing factor)
  - flight control,ruddervator - improper (cause)
  - maintenance,balancing - improper, other maintenance personnel (cause)
  - weather condition - turbulence (contributing factor)
  - flight control,ruddervator - flutter
  - fuselage,bulkhead - cracked
  - fuselage,skin - buckled

## Analysis

THE PLT RPRTD THAT DRG DSCNT, AT ABOUT 150 KTS, TURBULENCE WAS ENCTRD & THE RUDDER PEDALS BEGAN SHAKING UNCONTROLLABLY ALONG WITH THE WHOLE ACFT, MAINLY THE EMPENNAGE.  PULLING BACK ON THE CONTROL COLUMN & PUSHING ON THE RUDDER PEDALS CAUSED THE SHAKING TO SUBSIDE.  A LANDING WAS MADE WITHOUT FURTHER INCIDENT.  ALTHOUGH THE AFT FUSELAGE SKIN WAS WRINKLED, THE ACFT CONTINUED TO BE FLOWN FOR SVRL MONTHS.  A SUBSEQUENT INSPN DISCLOSED THAT ALL 4 CORNERS OF THE AFT FUSELAGE BULKHEAD WERE CRACKED.  THE STATIC BALANCE OF EACH RUDDERVATOR WAS MEASURED & FOUND TO BE EXCESSIVELY TAIL HEAVY.  ALSO, BOTH RUDDERVATOR TRIM TABS HAD BEEN INSTALLED IMPROPERLY, RESULTING IN FREE PLAY AT THE HINGE LINE.  NO LEAD BALANCING WASHERS WERE FOUND IN EITHER RUDDERVATOR COUNTERWEIGHT HOUSING.  THE THICKNESS OF PAINT ON THE RUDDERVATORS EXCEEDED THE MANUFACTURER'S FACTORY ACCEPTANCE CRITERIA.

## Aircraft

- Registration: [N3081V](https://openairdocs.org/deregistered/N3081V-2003-05-28), registration cancelled 2003-05-28, S/N D-496, built 1947 (OpenAirDocs)
- Reported make and model: BEECH 35
- Registry model: [Beech 35](https://openairdocs.org/model/beech-35) (registry code 1151502) (OpenAirDocs)
- Registry engine: [Continental E185 series](https://openairdocs.org/engine/continental-e185-series) (registry code 17014, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: D-496
- Engines: CONTINENTAL E-185-1 185 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Libby, Stephen R.
- Registered owner: Libby, Stephen R.
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 2, 2000
- Departed: LWS, LEWISTON, ID
- Destination: ALW, WALLA WALLA, WA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 20; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: right; flight hours: 94 total, 4 in this make and model, 55 as pilot in command

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: 55 °F

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.

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