# NTSB MIA95IA187: Boeing 737-3B7, N390US, Orlando, FL, July 18, 1995 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: July 18, 1995, 16:30 local (20:30 UTC) - Place: Orlando, FL - Coordinates: 28.419437, -81.299041 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=28.4194&lon=-81.2990&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 120 uninjured - Status: Completed, report September 3, 1996 - Report: Approved by Office Director - NTSB case key (mKey): 37677 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MIA95IA187 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/37677/pdf - Page: https://openairdocs.org/ntsb/MIA95IA187 ## Probable cause CONTAMINATION OF THE WIRING HARNESS AND ELECTRICAL CONNECTORS TO THE E-1-2 AND E-1-3 SHELF DISCONNECT BRACKETS IN THE ELECTRONICS COMPARTMENT, WHICH RESULTED IN AN ELECTRICAL FAULT AND AN UNCOMMANDED ROLL MALFUNCTION OF THE AUTOPILOT. A FACTOR RELATING TO THE INCIDENT WAS: INADEQUATE MAINTENANCE INSPECTION OF THE AIRCRAFT BY COMPANY MAINTENANCE PERSONNEL. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, descent - water and waste system - leak (contributing factor) - door,passenger - leak (contributing factor) - automatic flight control system (afcs) - contamination,other than water (cause) - automatic flight control system (afcs) - contamination,water (cause) - maintenance,inspection - inadequate, company maintenance personnel (contributing factor) - autopilot/flight director - malfunction (cause) ## Analysis THE FLIGHT EXPERIENCED AN UNCOMMANDED ROLL TO THE LEFT DURING DESCENT FOR LANDING. THE FLIGHT CREW DISENGAGED THE AUTOPILOT AND YAW DAMPER, BUT REENGAGED THE YAW DAMPER SINCE THERE WAS NO APPARENT YAW PROBLEM. THE DESCENT WAS CONTINUED AND A LANDING WAS MADE WITHOUT FURTHER INCIDENT. EXAMINTATION REVEALED THE CONNECTOR PLUGS AND WIRING HARNESS TO THE E-1-2 AND E-1-3 SHELF DISCONNECT BRACKETS IN THE ELECTRONICS COMPARTMENT WERE CONTAMINATED WITH WATER AND A BLUE RESIDUE. THE SOURCES OF CONTAMINATION WERE WATER FROM A CURRENT MAIN CABIN DOOR LEAK AND BLUE RESIDUE FROM A PREVIOUS LEAK OF THE FORWARD LAVATORY. ## Factual narrative On July 18, 1995, about 1630 eastern daylight time, a Boeing 737-3B7, N390US, registered to and operated by USAIR, Inc., as flight 855, a 14 CFR Part 121 scheduled domestic passenger service from Pittsburgh, Pennsylvania, to Orlando, Florida, experienced an uncontrolled roll to the left during descent for landing. Visual meteorological conditions prevailed at the time and an instrument flight rules flight plan was filed. The aircraft was not damaged and the airline transport-rated pilot, first officer, 3 flight attendants, and 115 passengers were not injured. The flight originated from Pittsburgh, on July 18, 1995, about 1504. The captain stated that about 65 nautical miles north of Ormond Beach, Florida, the flight was descending through 28,000 feet. The "A" autopilot system was on longitudinal navigation and vertical speed was selected for pitch control. The aircraft suddenly rolled hard to the left to about 25 degrees of bank angle. He overrode the roll with aileron control and returned the aircraft to wings level. The aircraft again rolled to the left and he disengaged the autopilot and yaw dampener. He reengaged the yaw dampener, left the autopilot off, and continued the flight to Orlando, without further incident. Examination of the aircraft showed the connector plugs and wiring harness to the E-1-2 and E-1-3 shelf disconnect brackets in the electronics compartment were contaminated with blue residue and water. The flight control computers and flight management computer mounts on these shelves. Evidence indicated the forward lavatory located above the electronics compartment had leaked at one time but was not currently leaking. Additionally, the main cabin door drain was found to not be properly sealed and water was leaking from the drain and dripping on to the wiring harness and migrating into the connectors. The flight control computer, and roll actuators were removed from the aircraft and tested. No failures which would cause an uncommanded roll were noted. For additional information see attached Boeing Commercial Airplane Company report, the Honeywell test report, and the FAA test report. ## Aircraft - Registration: [N390US](https://openairdocs.org/deregistered/N390US-2021-10-30), registration cancelled 2021-10-30, S/N 23312 (OpenAirDocs) - Reported make and model: Boeing 737-3B7 - Registry model: [Boeing 737-3B7](https://openairdocs.org/model/boeing-737-3b7) (registry code 138447F) (OpenAirDocs) - Registry engine: [CFM International CFM56 series](https://openairdocs.org/engine/cfm-international-cfm56-series) (registry code 13802, turbo-fan) (OpenAirDocs) - Category: Airplane - Serial number: 23312 - Airframe hours: 29494 - Engines: GE CFM56-3 22000 lbs thrust turbo fan - Damage: No damage - Flight: Part 121 - Registered owner: Usair - Airworthiness certificate: Standard, Transport - Last inspection: AAIP, July 18, 1995, 6 hours before - Departed: PIT, PITTSBURGH, PA - Destination: MCO - Flight plan: IFR ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 49; flight instructor, flight engineer, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--w/ waivers/lim; seat: left; flight hours: 14,651 total, 5 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 160° at 12 knots - Visibility: 10 statute miles - Lowest ceiling: 14,000 ft broken - Temperature: 82 °F, dew point 73 °F - Altimeter: 29.00 inHg - Observed at: MCO, 110 nm away ## 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 19950718026339I](https://openairdocs.org/incident/19950718026339I), Jul 18, 1995: Boeing 737300, Orlando, FL. Uncommanded roll at FL280. Descending. Disconnected autopilot and yaw dampner. Descent at 290 knots at 1000 fpm. 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.