# NTSB DEN91FA098: Boeing 707-323C, N8404, Denver, CO, July 9, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Field investigation · Final report
- Date: July 8, 1991, 20:36 local (Jul 9, 1991, 02:36 UTC)
- Place: Denver, CO
- Coordinates: 39.669612, -105.089347 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=39.6696&lon=-105.0893&mi=10
- Phase of flight: [Takeoff](https://openairdocs.org/ntsb-phases/300) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 6 uninjured
- Status: Completed, report July 13, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18028
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN91FA098
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18028/pdf
- Page: https://openairdocs.org/ntsb/DEN91FA098

## Probable cause

IMPROPER OVERHAUL OF THE NOSE GEAR ASSEMBLY BY OTHER MAINTENANCE PERSONNEL.

## Sequence of events

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

- Airframe/component/system failure/malfunction, takeoff - roll/run
  - landing gear,nose gear strut - separation (cause)
  - maintenance,overhaul - improper, other maintenance personnel (cause)
- Gear not extended, landing
  - landing gear,nose gear - missing

## Analysis

DURING ROTATION ON THE TAKEOFF ROLL, THE NOSE LANDING GEAR CAME OFF THE AIRPLANE AND REMAINED ON THE GROUND.  AS THE AIRCRAFT PASSED OVER THE NOSE LANDING GEAR ASSEMBLY, DAMAGE OCCURRED TO THE BELLY OF THE AIRCRAFT. TAKEOFF WAS COMPLETED AND AN EMERGENCY LANDING WAS CONDUCTED WITH THE MAIN LANDING GEAR AND THE STUB OF THE NOSE LANDING GEAR SHOCK STRUT EXTENDED.  DISASSEMBLY OF THE SHOCK STRUT INNER CYLINDER REVEALED THE ABSENCE OF SEVERAL PARTS.  THE AREA WHERE THESE PARTS ARE LOCATED IS A SEALED AREA THAT WAS NOT COMPROMISED.  THIS DISCREPANCY ALLOWED A RETENTION NUT TO BACK OFF WHICH RESULTED IN NOSE GEAR SEPARATION.  THE NOSE GEAR ASSEMBLY WAS OVERHAULED ON 9/4/85.

## Aircraft

- Registration: [N8404](https://openairdocs.org/deregistered/N8404-1994-06-23), registration cancelled 1994-06-23, S/N 19584 (OpenAirDocs)
- Reported make and model: BOEING 707-323C
- Registry model: [Boeing 707-323C](https://openairdocs.org/model/boeing-707-323c) (registry code 138367D) (OpenAirDocs)
- Category: Airplane
- Serial number: 19582LINE663
- Engines: P&W JT3D-3B 18500 horsepower turbo fan
- Damage: Substantial damage
- Flight: Part 121
- Operator: Southern Air Transport (Sat)
- Destination: MCI, KANSAS CITY, MO
- Flight plan: IFR
- Airport: DEN, Stapleton International, runway 17, 12,000 × 200 ft, concrete

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 50; airline transport; airplane ratings: multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; flight hours: 10,271 total, 3,138 in this make and model, 241 in the last 90 days, 78 in the last 30 days, 3 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Dusk
- Wind: 190° at 5 knots
- Visibility: 50 statute miles
- Lowest ceiling: 25,000 ft broken

## 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 19910708026509A](https://openairdocs.org/incident/19910708026509A), Jul 8, 1991: Boeing 707323C, Denver, CO, Substantial damage. Nose wheel strut and inner cylinder departed on takeoff. Damaged underside aircraft. Nut holding cylinder came off.

## Other investigations on N8404 (1)

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.

- [NTSB FTW87LA113](https://openairdocs.org/ntsb/FTW87LA113), May 1, 1987: Boeing 707-323C (N8404), Oklahoma City, OK, substantial damage

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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