# Incident 19991209034689I: Doug DC931, Dallas-Ft Worth, TX, December 9, 1999 - Type: FAA incident report (Accident/Incident Data System), as reported - Date: December 9, 1999, 17:18 local time - Place: Dallas-Ft Worth, TX - Airport: Dallas-Fort Worth International - Phase of flight: Climb - Operating rules: Air carrier (Part 121) - Operator: NWAA - Location: 32.8972° N, 97.0377° W: Placed by OpenAirDocs at DALLAS-FORT WORTH INTL (DFW), within about a mile (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=32.8972&lon=-97.0377&mi=10 - Aircraft: N8945E, a cancelled registration (https://openairdocs.org/deregistered/N8945E-2010-09-23) (OpenAirDocs) - Registry model: Douglas DC-9-31 (registry code 3022065, https://openairdocs.org/model/douglas-dc-9-31) (OpenAirDocs) - Registry engine: Pratt & Whitney JT8D-1 (registry code 52044, https://openairdocs.org/engine/pratt-whitney-jt8d-1) (OpenAirDocs) - Reported make and model: DOUG DC931 - FAA source: FAA Aviation Safety Information Portal (https://asip.faa.gov/) - Page: https://openairdocs.org/incident/19991209034689I ## Narrative As the FAA filed it, in capitals; the FAA replaces private details with ^PRIVACY DATA OMITTED^. (-23) NORTHWEST AIRLINES HAS BEGUN TO MODIFY IT'S DC-9 AIRCRAFT WITH A HAMILTON STANDARD ELECTRONIC DUAL CABIN PRESSURIZATION SYSTEM. THIS MODIFICATION IS APPROVED UNDER SANTA BARBARA AEROSPACE DAS/STC PROJECT #DAS14NM128. AN UPGRADED NORTHWEST DC-9-31, WHILE ON CLIMB-OUT FROM DALLAS/FT.WORTH, TEXAS (DFW) AT 14,000 FEET, EXPERIENCED A CABIN AUTO FAIL WARNING LIGHT WITH A SUBSEQUENT CABIN PRESSURE ANNUNCIATOR LIGHT, ALONG WITH DEPLOYMENT OF THE CABIN OXYGEN MASKS. THE FLIGHT CREW PERFORMED THE CABIN PRESSURE LOSS AND CABIN AUTO FAIL PROCEDURES; HOWEVER, WERE UNABLE TO REGAIN AUTO PRESSURE CONTROL. A RETURN TO DFW WAS MADE. THE AIRCRAFT WAS FERRIED TO MINNEAPOLIS FOR REQUIRED MAINTENANCE. NORTHWEST MAINTENANCE FOUND ONE CONTROLLER FAULTED, REPLACED BOTH CONTROLLERS, ACCOMPLISHED REQUIRED PRESSURE CHECKS WHICH WERE SATISFACTORY, AND RETURNED THE AIRCRAFT TO SERVICE. THE AIRCRAFT MADE ONE SUCCESSFUL REVENUE FLIGHT TO KANSAS CITY (MCI). WHILE ON DEPARTURE FROM MCI AT 17,000 FEET THE PRESSURIZATION SYSTEM CYCLED BACK AND FORTH +2000 FEET PER MINUTE TO -2000 FEET PER MINUTE AS THE OUTFLOW VALVE CYCLED FROM CLOSED TO OPEN. THE AIRCRAFT DESCENDED TO 10,000 FEET AND CONTINUED TO MINNEAPOLIS. MAINTENANCE FOUND BOTH CONTROLLERS FAULTED WITH CODE 51. IT SHOULD BE NOTED THAT THE AIRCRAFT, TWO DAYS PRIOR, HAD BEEN RELEASED FROM MAJOR STRUCTURAL UPGRADES INCLUDING REPLACEMENT OF THE BELLY SKIN JUST AFT OF THE E & E COMPARTMENT WHERE THE PRESSURIZATION CONTROLLERS ARE INSTALLED. THE NEW SKIN CONTAINED THE #1 ATC ANTENNA, #1 AND #2 DME ANTENNAS AND THE LOWER TCAS ANTENNA. HAMILTON STANDARD WAS CONTACTED. NORTHWEST AIRLINES FOUND A SIMILAR OCCURRENCE ON A BOEING 737. NORD-MICRO, THE MANUFACTURER OF THE CONTROLLERS AND A DIVISION OF HAMILTON STANDARD, HAD ISSUED SERVICE BULLETIN #19971-21-004 (COPY ATTACHED). THE SB ADDRESSES THE FACT THAT THE BOEING 737 DIGITAL CABIN PRESSURE CONTROL SYSTEM CAN BE AFFECTED BY EXCESSIVE RF RADIATION FROM THE ATC SYSTEM. THE SB INVOLVES APPLYING COPPER TAPE TO THE FRONT CORNER AND EDGES OF THE PRESSURE CONTROLLERS. WHILE THE DC-9 AND BOEING 737 CONTROLLERS HAVE DIFFERENT PART NUMBERS, THE BOSES ARE CONSTRUCTED THE SAME AND COULD BE EXCHANGED IF THE PARAMETERS FOR THE PRESSURIZATION ENVELOPE WERE SIMILAR. NORTHWEST AIRLINES CHANGED BOTH PRESSURIZATION CONTROLLERS, REPLACED THE #1 ATC ANTENNA, #1 AND #2 DME ANTENNAS AND THE LOWER TCAS ANTENNA, ALONG WITH ASSURING PROPER BONDING BETWEEN THE ANTENNAS AND SKIN. THE AIRCRAFT WAS RETURNED TO SERVICE AND HAS BEEN OPERATING WITHOUT PRESSURIZATION PROBLEMS. ^PRIVACY DATA OMITTED^ ## Other reports on N8945E (3) Matched to the same aircraft by N-number and date. - [Incident 20040130002749I](https://openairdocs.org/incident/20040130002749I), Jan 30, 2004: Doug DC931 (N8945E), Cleveland, OH, Minor damage. (-23) Tow-truck driver collided with aircraft RH #5 wing slat while driving away after disconnecting tow bar. Canopy of tug (hough/T300SL) punctured a 4 x 4.5… - [Incident 19950816029109I](https://openairdocs.org/incident/19950816029109I), Aug 16, 1995: Doug DC931 (N8945E), Syracuse, NY. FL300 overheated pack and depressurization. Descended. Used manual pressure system. Auto system put on MEL list. - [Incident 19790507026179I](https://openairdocs.org/incident/19790507026179I), May 7, 1979: Doug DC931 (N8945E), East Windsor Lo, CT, Minor damage. Nose gear tire blew on landing. Replaced tire and wheel assembly PN90WH236. From the FAA Accident/Incident Data System. Reports are matched to registry aircraft by N-number and event date, checked against the reported make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. For accidents, the NTSB's own investigation is the fuller record. --- 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.