# NTSB BFO93IA175: Boeing 757-200ER, N757NA, Jamaica, NY, September 13, 1993 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: September 13, 1993, 08:55 local (12:55 UTC) - Place: Jamaica, NY - Coordinates: 40.650669, -73.790794 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=40.6507&lon=-73.7908&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 85 uninjured - Status: Completed, report October 20, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 8766 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=BFO93IA175 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8766/pdf - Page: https://openairdocs.org/ntsb/BFO93IA175 ## Probable cause THE FAILURE OF THE LEFT HYDRAULIC PRESSURE SWITCH, WHICH CAUSED THE LEFT YAW DAMPER MODULE TO BECOME INOPERATIVE RESULTING IN UNCOMMANDED RUDDER MOVEMENTS DURING FLIGHT. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - normal - flt control syst,rudder control - inoperative (cause) ## Analysis DURING CRUISE FLIGHT, A RUDDER RATIO WARNING LIGHT APPEARED, FOLLOWED BY UNCOMMANDED RIGHT RUDDER MOVEMENT AND LEFT AILERON INPUT. THE AIRPLANE REMAINED UNDER CONTROL AND THE CREW COUNTERACTED THE RUDDER MOVEMENT MANUALLY. THE CAPTAIN ELECTED TO ABORT THE FLIGHT AND LANDED SAFELY AT THE DEPARTURE AIRPORT. THE RUDDER RATIO WARNING WAS DISPLAYED ON TWO SUBSEQUENT FLIGHTS, DESPITE REPEATED ATTEMPTS TO RESOLVE THE DISCREPANCY. AFTER THE FOURTH WARNING WAS DISPLAYED IN ABOUT TWO MONTHS, AN EXAMINATION OF THE LEFT YAW DAMPER MODULE REVEALED A MALFUNCTION IN THE LEFT HYDRAULIC PRESSURE SWITCH. THE UNIT WAS REMOVED AND REPLACED. NO FURTHER INCIDENTS INVOLVING A RUDDER RATIO WARNING WERE REPORTED. ## Factual narrative On September 13, 1993, about 0855 hours eastern daylight time, N757NA, a Boeing 757-200ER, operating as North American Airlines Flight 5, had a flight control problem during cruise flight. The flight had departed from John F. Kennedy International Airport (JFK), Jamaica, New York, en route to San Francisco, California, but returned to JFK and landed uneventfully. None of the eight crewmembers or 77 passengers were injured. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed. The flight was conducted under 14 CFR 121. According to a FAA aviation safety inspector, a "rudder ratio" warning message was displayed in the cockpit as the airplane climbed through Flight Level 270 after departure. The crew performed the published company troubleshooting procedures, including resetting the rudder ratio circuit breaker light, and the warning was eliminated. About one hour later during cruise flight at Flight Level 350, the warning was displayed once again followed by gradual uncommanded right rudder movement. The autopliot was engaged at the time and two units of left aileron were inputted by the autopilot. The airplane remained under control and the crew counteracted the rudder movement manually. The captain elected to abort the flight and return to JFK. An examination of the airplane's electrical system revealed that the fault ball on right rudder control module had popped out. The module was reset and successfully passed a functional check. The airplane was placed back into service. The rudder ratio warning message was again displayed on two flights subsequent to this event. The flights terminated uneventfully. According to company maintenance records, maintenance activities to correct the situation during these events involved readjustment of the rigging, functional testing of the fault module, and replacement of the rudder ratio actuator. The airplane was placed back into service after each of these events. On November 19, 1993, the rudder ratio light was displayed for the fourth time in about two months. An examination of the left yaw damper module revealed a malfunction in the left hydraulic pressure switch. The unit was removed and replaced. No further incidents involving a rudder ratio problem were reported. ## Aircraft - Registration: [N757NA](https://openairdocs.org/deregistered/N757NA-2005-06-28), registration cancelled 2005-06-28, S/N 24567, built 1990 (OpenAirDocs) - Reported make and model: BOEING 757-200ER - Registry model: [Boeing 757-23A](https://openairdocs.org/model/boeing-757-23a) (registry code 1384967) (OpenAirDocs) - Registry engine: [Rolls-Royce RB211-535E437](https://openairdocs.org/engine/rolls-royce-rb211-535e437) (registry code 54053, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 24567 - Airframe hours: 10274 - Engines: Rolls-Royce RB211-535E4 turbo fan - Damage: No damage - Flight: Part 121 - Operator: North American Airlines - Registered owner: Ansett Worldwide Aviation, USA - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, August 31, 1993, 184 hours before - Departed: JFK - Destination: SFO, SAN FRANCISCO, CA - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 50; commercial, 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: 19,300 total, 2,300 in this make and model, 150 in the last 90 days, 50 in the last 30 days, 4 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 230° at 11 knots - Visibility: 15 statute miles - Lowest ceiling: 13,000 ft broken - Temperature: 72 °F, dew point 57 °F - Altimeter: 30.00 inHg - Observed at: JFK ## FAA reports on this event (1) The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs). - [Incident 19930913038109I](https://openairdocs.org/incident/19930913038109I), Sep 13, 1993: Boeing 75723A, New York, NY. Rudder ratio eicas message came on at alitude. Returned. Landed safely. Replaced righ rudder contro module. 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. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.