# NTSB DEN86LA262: Beech 60, N3694D, Boulder, CO, September 30, 1986

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: September 29, 1986, 18:45 local (Sep 30, 1986, 00:45 UTC)
- Place: Boulder, CO
- Location: 40.0244° N, 105.2513° W: Placed by OpenAirDocs: center of Boulder, CO, within about 6 miles (OpenAirDocs)
- Nearby events: https://openairdocs.org/map.md?lat=40.0244&lon=-105.2513&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 17056
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN86LA262
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/17056/pdf
- Page: https://openairdocs.org/ntsb/DEN86LA262

## Sequence of events

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

- Airframe/component/system failure/malfunction, landing - roll
  - landing gear,normal brake system - failure,partial (cause)
  - proper alignment - not possible, pilot in command (cause)
  - fluid,hydraulic - leak (contributing factor)
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - rough/uneven (cause)

## Analysis

AT TOUCHDOWN, THE PLT APPLIED BRAKES NORMALLY. HE NOTICED SOFTENING OF THE LEFT BRAKE PEDAL AND THE ACFT TURNED RIGHT LEAVING THE RWY AND INTERSECTING A TAXIWAY AT APRX A 30 DEGREE ANGLE. THE TAXIWAY HAD A SIX INCH RISE AT THE EDGE WHICH CAUSED THE LEFT MAIN GEAR TO COLLAPSE UPON IMPACT. INVESTIGATION REVEALED THAT THE BRAKE FLUID LEAKED OUT DURING FLT BECAUSE OF A COCKED BRAKE PUCK.

## Aircraft

- Registration: [N3694D](https://openairdocs.org/aircraft/N3694D), registered now, S/N P-552, built 1980 (OpenAirDocs)
- Reported make and model: BEECH 60
- Registry model: [Beech B-60](https://openairdocs.org/model/beech-b-60) (registry code 1153605) (OpenAirDocs)
- Category: Airplane
- Serial number: P-552
- Airframe hours: 1188
- Engines: LYCOMING TIO-541-E1C4 380 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Robert G. Knollenberg
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, October 17, 1985, 88 hours before
- Departed: ASE, ASPEN, CO
- Destination: 1V5, BOULDER, CO
- Flight plan: VFR
- Airport: IV5, Boulder

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 47; private; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 3, unknown; seat: left; flight hours: 1,455 total, 23 in this make and model, 1,294 as pilot in command, 44 in the last 90 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Night/dark
- Wind: 310° at 13 knots
- Visibility: 25 statute miles
- Lowest ceiling: 1,500 ft broken
- Temperature: 61 °F, dew point 36 °F
- Altimeter: 29.00 inHg
- Observed at: BJC

## 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 19860929048829A](https://openairdocs.org/incident/19860929048829A), Sep 29, 1986: Beech B60, Boulder, CO, Substantial damage. The aircraft veered off the runway during landing. Brake puck cocked in the cylinder, allowing depletion of fluid.

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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