# NTSB CEN24LA227: Beech D55, N321N, Colorado Springs, CO, June 11, 2024

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Class 4 · Limited · Final report
- Date: June 10, 2024, 21:00 local (Jun 11, 2024, 03:00 UTC)
- Place: Colorado Springs, CO · Runway 17R, off right side of runway between Taxiways A1 and A2.
- Coordinates: 38.805817, -104.70077 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.8058&lon=-104.7008&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Defining event: [Landing-flare/touchdown: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330)
- Highest injury: Minor injuries
- Injuries: 1 minor, 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- Investigation class: Class 4 - Basic report with no Prelim publish
- NTSB office: Central Region
- Parties: Federal Aviation Administration - Denver FSDO
- NTSB case key (mKey): 194486
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN24LA227
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/194486/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=194486
- Page: https://openairdocs.org/ntsb/CEN24LA227

## Probable cause

The deflated right main landing gear tire due to a sidewall puncture made by an unknown object, which led to the pilot’s loss of directional control and the landing gear collapse during landing roll.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Landing gear system: tire casing](https://openairdocs.org/ntsb-findings/01023244): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Beech D55, 2 cases](https://openairdocs.org/ntsb-findings/01023244/cases.md?model=1152730), [All aircraft, 36 cases](https://openairdocs.org/ntsb-findings/01023244/cases.md)
- [Landing gear system: tube](https://openairdocs.org/ntsb-findings/01023245): Aircraft › Aircraft systems · Damaged/degraded (probable cause); cases with it: [Beech D55, 2 cases](https://openairdocs.org/ntsb-findings/01023245/cases.md?model=1152730), [All aircraft, 19 cases](https://openairdocs.org/ntsb-findings/01023245/cases.md)
- [Landing gear system: gear extension and retract sys](https://openairdocs.org/ntsb-findings/01023230): Aircraft › Aircraft systems · Capability exceeded (probable cause); cases with it: [Beech D55, 1 case](https://openairdocs.org/ntsb-findings/01023230/cases.md?model=1152730), [All aircraft, 416 cases](https://openairdocs.org/ntsb-findings/01023230/cases.md)
- [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [Beech D55, 1 case](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=1152730), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md)
- [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Ability to respond/compensate (probable cause); cases with it: [Beech D55, 1 case](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=1152730), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md)
- [Use of equip/info: aircraft control](https://openairdocs.org/ntsb-findings/02063040): Personnel issues › Task performance · Pilot (probable cause); cases with it: [Beech D55, 1 case](https://openairdocs.org/ntsb-findings/02063040/cases.md?model=1152730), [All aircraft, 9,295 cases](https://openairdocs.org/ntsb-findings/02063040/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Unknown: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [Beech D55, 2 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=1152730), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)
- [Landing-flare/touchdown: Sys/Comp malf/fail (non-power)](https://openairdocs.org/ntsb-events/330) (defining event); cases with it: [Beech D55, 2 cases](https://openairdocs.org/ntsb-events/330/sequence.md?model=1152730), [All aircraft, 994 cases](https://openairdocs.org/ntsb-events/330/sequence.md)
- [Landing-landing roll: Loss of control on ground](https://openairdocs.org/ntsb-events/230); cases with it: [Beech D55, 1 case](https://openairdocs.org/ntsb-events/230/sequence.md?model=1152730), [All aircraft, 4,585 cases](https://openairdocs.org/ntsb-events/230/sequence.md)
- [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [Beech D55, 2 cases](https://openairdocs.org/ntsb-events/094/sequence.md?model=1152730), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md)
- [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Beech D55, 2 cases](https://openairdocs.org/ntsb-events/300/sequence.md?model=1152730), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md)

## Analysis

The flight instructor and the pilot-receiving-instruction were conducting a nighttime currency/proficiency flight when, after an uneventful landing flare and touchdown, the airplane began to vibrate and veer right during the landing roll. The pilot-receiving-instruction, who was the pilot flying during the landing, released toe brake input but the vibration increased as the airplane continued to veer right. Ultimately, the right main landing gear collapsed, and the airplane came to rest upright in the grass adjacent to the runway. The right wing main spar was substantially damaged when the right wing struck the ground after the landing gear collapsed. Examination of the right main landing gear tire and its tube revealed a sidewall puncture. The puncture was made by an unknown small, sharp object, which left a clean cut on the tube sidewall that measured about 0.25-inch long with the tube deflated, and 0.375-inch long when the tube was reinflated. During the landing roll, it is likely that the tube lost enough pressure that it began to move around the wheel rim until the valve stem severed and there was total loss of remaining tire pressure. The increasing vibration felt by the pilots during landing roll is consistent with a progressive loss of tire pressure, and the increased drag from the deflated right tire would explain airplane’s tendency to veer right. The right main landing gear likely collapsed when the over-center down lock assembly disengaged due to an excessive sideload during the right swerve.

## Aircraft

- Registration: [N321N](https://openairdocs.org/aircraft/N321N), registered now, S/N TE-583, built 1968 (OpenAirDocs)
- Reported make and model: BEECH D55
- Registry model: [Beech D55](https://openairdocs.org/model/beech-d55) (registry code 1152730) (OpenAirDocs)
- Registry engine: [Continental IO-520 series](https://openairdocs.org/engine/continental-io-520-series) (registry code 17032, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: TE-583
- Year built: 1968
- Airframe hours: 4891
- Engines: Continental IO-520-C 285 horsepower reciprocating; Continental IO-520-C 285 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Peterson Space Force Aero Club, doing business as Rocky Mountain Flight Training Center
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 10, 2024, 1 hours before
- Departed: COS, Colorado Springs, CO
- Destination: COS, Colorado Springs, CO
- Flight plan: VFR
- Airport: COS, City of Colorado Springs Municipal Airport, runway 17R, 11,022 × 150 ft, asphalt
- Equipment: Stall warning system, ADS-B, Auto-pilot, Electronic flight bag or handheld device, Electronic primary flight display

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; injuries: minor; military, commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 2, without waivers/limitations; last flight review May 9, 2024; seat: left; restraint: 4-point; flight hours: 1,399 total, 30 in this make and model, 1,399 as pilot in command, 38 in the last 90 days, 2 in the last 30 days, 2 in the last 24 hours
- Flight instructor; age 57; injuries: none; airline transport, military; airplane ratings: multi-engine land, single-engine land, single-engine sea; instrument ratings: airplane; medical: class 2, with waivers/limitations; last flight review May 19, 2024; seat: right; restraint: 4-point; flight hours: 5,153 total, 106 in this make and model, 4,706 as pilot in command, 36 in the last 90 days, 10 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Night
- Wind: 190° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: 20,000 ft broken
- Temperature: 68 °F, dew point 55 °F
- Altimeter: 30.08 inHg
- Observed at: COS, 1 nm away
- METAR: METAR KCOS 110254Z 19004KT 10SM FEW120 BKN200 BKN250 20/13 A3008 RMK AO2 SLP117 T02000128 50005 $=

## 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 20240610007609A](https://openairdocs.org/incident/20240610007609A), Jun 10, 2024: Beech D55, Colorado Spring, CO, Substantial damage. On June 10, 2024 at 2100 MDT, a Beech D55 baron, departed off the right side of runway 17R at the Colorado Springs municipal airport (kcos) approximately 2260…

## Docket (3 files)

The files NTSB released with the investigation on January 21, 2025, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=194486. 5.5 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 3.9 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18148371&FileExtension=pdf&FileName=01%20-%20NTSB%206120_1_Redacted-Rel.pdf
- Airplane operator accident narrative and examination summary (item 2, PDF, 22 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18148123&FileExtension=pdf&FileName=02%20-%20Airplane%20Operator%20Accident%20Narrative%20and%20Examination%20Summary-Rel.pdf
- Investigation photographs (item 3, PDF, 3 pages, 2 photos, 498 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18148675&FileExtension=pdf&FileName=03%20-%20Investigation%20Photographs-Rel.pdf

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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