# NTSB NYC93IA113: Short Brothers SD3-60-200, N711HJ, Atlantic City, NJ, June 14, 1993 - Type: NTSB incident investigation - Classification: Incident · No injuries · Incident investigation · Final report - Date: June 14, 1993, 17:02 local (21:02 UTC) - Place: Atlantic City, NJ - Location: 40.0654° N, 74.5772° W: Placed by OpenAirDocs from NTSB’s distance and direction from ATLANTIC CITY INTL (ACY), within about 13 miles (OpenAirDocs) - Nearby events: https://openairdocs.org/map.md?lat=40.0654&lon=-74.5772&mi=10 - Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping) - Highest injury: No injuries - Injuries: 21 uninjured - Status: Completed, report September 13, 1994 - Report: Approved by Office Director - NTSB case key (mKey): 38597 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=NYC93IA113 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/38597/pdf - Page: https://openairdocs.org/ntsb/NYC93IA113 ## Probable cause A malfunction of the cargo fire warning system which resulted in a false alarm. ## Sequence of events In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf). - Airframe/component/system failure/malfunction, cruise - normal - fire warning system,cargo - false indication (cause) ## Analysis THE AIRPLANE WAS CRUISING AT 6000 FEET WHEN THE AFT BAGGAGE COMPARTMENT FIRE LIGHT ILLUMINATED IN THE COCKPIT. EXTINGUISHING AGENT WAS DIRECTED TO THE AFT BAGGAGE COMPARTMENT BY THE FLIGHT ATTENDANT PLACING THE NOZZLE OF A HAND HELD FIRE EXTINGUISHER THROUGH A RECEPTACLE WITH A SEALING 'O' RING, LOCATED ON THE AFT CABIN BULKHEAD. THE FLIGHT ATTENDANT SAID THE EXTINGUISHING AGENT BLEW BACK ONTO HER HANDS. SHE THEN TRIED TWO OTHER EXTINGUISHERS WITH THE SAME RESULTS. AFTER LANDING, EXAMINATION OF THE BAGGAGE COMPARTMENT FOUND NO EVIDENCE OF A FIRE. THE FIRE WARNING WAS ATTRIBUTED TO A FALSE INDICATION FROM THE SMOKE DETECTOR IN THE AFT BAGGAGE COMPARTMENT. POST INCIDENT TESTING BY THE FAA AND THE OPERATOR FOUND THAT WHEN THE FIRE EXTINGUISHER NOZZLE DID NOT FIT THORUGH THE SEALING 'O' RING, EXTINGUISHING AGENT WOULD SPRAY BACK ON THE PERSON HOLDING THE FIRE EXTINGUISHER. WHEN THE SEALING 'O' RING WAS LUBRICATED, AND THE NOZZLE WAS CHAMFERED IN ACCORDANCE WITH THE MANUFACTURERS SERVICE BULLETIN, THE EXTINGUISHER NOZZLE FIT THROUGH THE SEALING 'O' RING EASILY AND NO LEAKAGE OCCURRED. ## Factual narrative On Monday, June 14, 1993, at 1702 eastern daylight time, a Short Brothers SD3-60-200, N711HJ, operating as Allegheny Commuter Flight 3575, made a precautionary landing at Atlantic City, New Jersey, due to a fire warning in the aft baggage compartment. There was no damage to the airplane or injuries to the crew and 18 passengers. Visual meteorological conditions prevailed and flight 3575 was operating on an instrument flight plan under 14 CFR 121. Flight 3575 was a scheduled flight operating between Philadelphia, Pennsylvania, and New Haven, Connecticut. While cruising at 6000 feet, the aft baggage compartment fire light illuminated in the cockpit. Fire extinguishing agent is directed to the aft baggage compartment by placing the nozzle of a hand held fire extinguisher through a receptacle with a sealing "O" ring on the aft cabin bulkhead. The fire extinguisher is then actuated and the extinguishing agent travels through a line to the baggage compartment. In a written report, the captain stated: ...the smoke aft light illuminated...Jim Town, my first officer, pulled out the Emergency checklist. He notified Donna Smith, the fight attendant, to empty two fire extinguisher bottles into the back bay port...A few minutes later Jim informed me that Donna had trouble with the extinguishers blowing back when used. I gave her the flight compartment extinguisher to use. She came back later, she said she used about half a bottle and had the same problem. She informed us that no smoke was coming from the back and no heat was detected at the aft wall.... The flight attendant stated: ...I did as I was told, the fire ex.[extinguishing agent] blew back into my face. I reread the instructions to make sure I was operating it correctly and tried again. Went to the second one with the same result. Called the Captain & asked if my actions had any effect. Told the FO[First Officer] I'd need his fire extinguisher & told Captain that there was no smoke or heat...I forced the third extinguisher mostly in & wrapped the fire extinguisher handle with paper towels to try to force more in. It was blowing back so much that it was frostbiting my hand through the paper towel. I stowed extinguishers.... After landing, the pilot stopped the airplane on the runway and deplaned the passengers through the passenger entry door. No evidence of a fire was found. The source of the false fire warning was found to be a failure of the Aft Baggage Bin Smoke Detector. In a telephone interview, Mr. Bob Walling, of Short Brothers (USA), said other operators had reported difficulty in getting a good seal with the extinguisher nozzle in the "O" ring. The fix was to lubricate the "O" ring with Dow Corning compound # 33, (DC-33). In addition, he said the fire extinguisher manufacturer had issued a service bulletin to modify the nozzles for easier entry. This was Service Bulletin 26-107, Revision 1, dated November 2, 1992, and issued by Fire Fighting Enterprises (U.K.) Ltd. A check with the operator revealed that neither of these had been accomplished. On June 25, 1993, the FAA conducted testing at the operator's facility, using a fire extinguisher with the nozzle modified in accordance with the service bulletin. In addition, the "O" ring the nozzle was placed through, had been lubricated with Dow Corning compound # 33. According to their report: ...Testing using a nozzle modified in accordance [with] the FFE Service Bulletin did not require excessive force and fully engaged the fire extinguisher with minimal effort, with no damage to the "O" Ring Seal. The use of lubricant with the modified nozzle did not appreciably change the force to engage the nozzle in the fire extinguisher system port.... ## Aircraft - Registration: [N711HJ](https://openairdocs.org/deregistered/N711HJ-2018-01-23), registration cancelled 2018-01-23, S/N SH3697 (OpenAirDocs) - Reported make and model: SHORT BROTHERS SD3-60-200 - Registry model: [Short Bros SD3-60](https://openairdocs.org/model/short-bros-sd3-60) (registry code 8100606) (OpenAirDocs) - Registry engine: [Pratt & Whitney Canada PT6A-60A](https://openairdocs.org/engine/pratt-whitney-canada-pt6a-60a) (registry code 52043, turbo-prop) (OpenAirDocs) - Category: Airplane - Serial number: SH3697 - Airframe hours: 15829 - Engines: P&W PT6A-65AR 1220 horsepower turbo prop - Damage: No damage - Flight: Part 121 - Operator: Pennsylvania Commuter, doing business as Allegheny Commuter/Usair Exp - Registered owner: US West Financial Services - Airworthiness certificate: Standard, Transport - Last inspection: Continuous airworthiness, May 28, 1993, 115 hours before - Departed: PHL, PHILADELPHIA, PA - Destination: HVN, NEW HAVEN, CT - Flight plan: IFR - Airport: ACY, Atlantic City, runway 22, 6,144 × 150 ft, asphalt ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 45; flight instructor, airline transport; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, valid medical--no waivers/lim.; seat: left; flight hours: 6,609 total, 1,206 in this make and model, 2,276 as pilot in command, 210 in the last 90 days, 71 in the last 30 days, 2 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Visibility: 12 statute miles - Lowest ceiling: none - Temperature: 73 °F, dew point 50 °F - Altimeter: 30.00 inHg - Observed at: ACY, 42 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 19930614026129I](https://openairdocs.org/incident/19930614026129I), Jun 14, 1993: Stbros SD360, Atlantic City, NJ. Aft cargo smoke light on. Used fire extinguishers. Extinguishers malfunction. No fire or smoke. Landed safely. 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.