# NTSB FTW92IA184: Boeing 737-222, N12235, Oklahoma City, OK, July 15, 1992

- Type: NTSB incident investigation
- Classification: Incident · No injuries · Incident investigation · Final report
- Date: July 15, 1992, 16:15 local (21:15 UTC)
- Place: Oklahoma City, OK
- Coordinates: 35.420227, -97.390312 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.4202&lon=-97.3903&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 88 uninjured
- Status: Completed, report June 30, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 18391
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW92IA184
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/18391/pdf
- Page: https://openairdocs.org/ntsb/FTW92IA184

## Probable cause

HYDRAULIC FLUID EXHAUSTION DUE TO THE CHAFED 'A' SYSTEM HYDRAULIC LINE AND THE IMPROPER INSTALLATION BY UNKNOWN MAINTENANCE PERSONNEL OF THE 'B' SYSTEM LINE.

## Sequence of events

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

- Airframe/component/system failure/malfunction, approach - faf/outer marker to threshold (ifr)
  - fluid,hydraulic - exhaustion (cause)
  - hydraulic system,line - chafed (cause)
  - hydraulic system,line - incorrect (cause)
  - maintenance,installation - improper, unknown (cause)

## Analysis

THE AIRPLANE EXPERIENCED A DUAL HYDRAULIC SYSTEM FAILURE DURING FINAL APPROACH. THE CAPTAIN ELECTED TO GO AROUND AND LAND AT A NEARBY MILITARY AIRPORT THAT HAD LONGER RUNWAYS. THE LANDING WAS UNEVENTFUL. INVESTIGATION REVEALED THAT A HOLE HAD BEEN CHAFED THROUGH A RETURN LINE IN THE 'A' HYDRAULIC SYSTEM AT A BRACKET IN THE LEFT WHEEL WELL AREA. IT WAS ALSO DETERMINED THAT AN 'A' SYSTEM AND A 'B' SYSTEM RETURN LINE HAD BEEN CROSS CONNECTED IN THE AREA OF THE NO. 1 PYLON. THE CROSS CONNECTED LINES ALLOWED THE 'B' SYSTEM FLUID TO TRANSFER INTO THE 'A' SYSTEM AND VENT OVERBOARD.  BOTH HYDRAULIC SYSTEMS, INDICATIONS AND READINGS, AND TESTS WERE NORMAL UNTIL THE HOLE WAS CHAFED THROUGH THE 'A' SYSTEM LINE. A MAINTENANCE RECORD REVIEW COULD NOT DETERMINE AT WHAT POINT IN TIME THE LINES HAD BEEN REVERSED.

## Aircraft

- Registration: [N12235](https://openairdocs.org/deregistered/N12235-2000-01-06), registration cancelled 2000-01-06, S/N 19758 (OpenAirDocs)
- Reported make and model: BOEING 737-222
- Registry model: [Boeing 737-222](https://openairdocs.org/model/boeing-737-222) (registry code 1384473) (OpenAirDocs)
- Category: Airplane
- Serial number: 19758
- Airframe hours: 41106
- Engines: P&W JT8D-9 14500 lbs thrust turbo fan
- Damage: No damage
- Flight: Part 121
- Operator: Continental Airlines, Inc.
- Registered owner: Icci, Inc.
- Airworthiness certificate: Standard, Transport
- Last inspection: Continuous airworthiness, February 3, 1992, 74 hours before
- Departed: DEN, DENVER, CO
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 44; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 13,000 total, 800 in this make and model, 120 in the last 90 days, 40 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 10 statute miles
- Lowest ceiling: none

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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