NTSB Identification: CHI89FA183.
The docket is stored on NTSB microfiche number 41832.
Scheduled 14 CFR operation of AMERICAN AIRLINES
Accident occurred Tuesday, September 12, 1989 in CHICAGO, IL
Probable Cause Approval Date: 09/11/1992
Aircraft: McDonnell Douglas MD-80, registration: N244AA
Injuries: 2 Minor,108 Uninjured.

NTSB investigators either traveled in support of this investigation or conducted a significant amount of investigative work without any travel, and used data obtained from various sources to prepare this aircraft accident report.

DURING DESCENT A COMPLETE HYDRAULIC SYSTEM FAILURE OCCURRED. DURING THE LANDING ROLLOUT THE AIRPLANE RAN OFF THE SIDE OF THE RUNWAY & COLLIDED WITH A MANHOLE COVER COLLAPSING THE NOSE GEAR. THE POWER TRANSFER UNIT SHUTOFF VALVE, P/N 240695, FAILED; ONE OF THE DUAL VALVE BODY HALVES SEPARATED AT THE MOUNTING PLATE. THE VALVE HAD A KNOWN HISTORY OF FAILURES, AND A KIT VERSION OF A 'FIX' TO THE VALVE HAD BEEN AVAILABLE BY THE MANUFACTURER. THE FLIGHT MANUAL CAUTIONS THAT FOR LANDING WITH NO HYDRAULIC POWER, INCREASING AMOUNTS OF REVERSE THRUST SIGNIFICANTLY REDUCES RUDDER EFFECTIVENESS, AND IN THE EVENT OF DIRECTIONAL CONTROL PROBLEMS TO REDUCE REVERSE THRUST AS REQUIRED AND SELECT FORWARD IDLE IF NECESSARY TO MAINTAIN OR REGAIN CONTROL. DFDR READOUT SHOW THE APPLICATION OF THRUST GREATER THAN IDLE REVERSE DURING THE THE LANDING ROLLOUT.

The National Transportation Safety Board determines the probable cause(s) of this accident to be:

A LOSS OF HYDRAULIC SYSTEM PRESSURE DUE TO THE OPERATOR'S FAILURE TO REPLACE A SYSTEM COMPONENT THAT HAD A KNOWN HISTORY OF FAILURES, AND THE PILOT'S IMPROPER USE POWERPLANT CONTROLS RESULTING IN A DEGRADATION OF RUDDER EFFECTIVENESS. A CONTRIBUTING FACTOR WAS THE FAILURE OF THE POWER TRANSFER UNIT SHUTOFF VALVE.

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