A fokker 100 on final approach at 400 ft experiences explosive sound below cockpit seats on ground, ...

Attributes
ACN	526836
Time
Date	200110
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : zzz.airport
State Reference	US
Altitude	agl single value : 400
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Controlling Facilities	tower : zzz.tower
Operator	common carrier : air carrier
Make Model Name	Fokker 100
Operating Under FAR Part	Part 121
Flight Phase	descent : approach
Route In Use	approach : instrument precision
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : private pilot : multi engine pilot : instrument pilot : atp
Experience	flight time last 90 days : 240 flight time total : 13000 flight time type : 1200
ASRS Report	526836
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Events
Anomaly	aircraft equipment problem : critical other anomaly other anomaly other
Independent Detector	other flight crewa other flight crewb
Resolutory Action	aircraft : evacuated flight crew : declared emergency flight crew : landed in emergency condition
Consequence	other other other other
Supplementary
Problem Areas	Aircraft
Primary Problem	Aircraft

Narrative:

Flying the ILS approach and at approximately 400 ft AGL, I felt a loud explosive sound beneath my cockpit seat. The concussion reverberated in the cockpit. Air conditioning flow into the fltdeck was reduced considerably. A check of all wind screens was made and found intact. All engine instruments were normal, on touchdown, idle reverse was selected (normal procedure for us) and both thrust reversers indicated normal deployment. Wheel braking commenced at 100 KIAS with normal deceleration. The aircraft exited the runway on a high speed taxiway at approximately 30 KTS. Upon clearing the runway the fltdeck began filling with smoke. The smoke was not electrical in nature. The cockpit door was opened to check for smoke in cabin. Flight attendant's 'chimmed' the fltdeck at the same instant. Smoke became thicker in the fltdeck as we rolled to a stop on parallel taxiway. Cockpit windows were both opened. At this time captain and myself made the decision to evacuate the aircraft. Captain ordered 'evacuation checklist.' I donned my oxygen mask and went speaker/hot microphone and began reading my evacuate/evacuation checklist. When checklists were complete and engines were shutdown, the smoke began subsiding. Captain and myself unstraped and helped passengers evacuate the aircraft. Fwd slides were deployed and all passenger '48 and crew 5' egressed the aircraft. I was ordered by captain to gather all passengers off the acfts left forward nose about 30 yards. Only possible injuries at the same time was a sprained ankle from one of the passengers. Callback conversation with reporter revealed the following information: the reporter stated the airplane was a fokker 100 and the cause of the explosive sound was the left pack heat exchanger rupture. The reporter said the pack heat exchangers are located beneath the cockpit floor. The reporter said the pack compartment was filled with hot engine bleed air mixing with oil from the air cycle machine causing the cockpit and cabin smoke. The reporter said the aircraft was evacuated on the ground with only one passenger incurring a twisted ankle.

Original NASA ASRS Text

Title: A FOKKER 100 ON FINAL APCH AT 400 FT EXPERIENCES EXPLOSIVE SOUND BELOW COCKPIT SEATS ON GROUND, COCKPIT AND CABIN FILLED WITH SMOKE. SMOKE CAUSED BY RUPTURED LEFT PACK HEAD EXCHANGER.

Narrative: FLYING THE ILS APCH AND AT APPROX 400 FT AGL, I FELT A LOUD EXPLOSIVE SOUND BENEATH MY COCKPIT SEAT. THE CONCUSSION REVERBERATED IN THE COCKPIT. AIR CONDITIONING FLOW INTO THE FLTDECK WAS REDUCED CONSIDERABLY. A CHK OF ALL WIND SCREENS WAS MADE AND FOUND INTACT. ALL ENG INSTRUMENTS WERE NORMAL, ON TOUCHDOWN, IDLE REVERSE WAS SELECTED (NORMAL PROCEDURE FOR US) AND BOTH THRUST REVERSERS INDICATED NORMAL DEPLOYMENT. WHEEL BRAKING COMMENCED AT 100 KIAS WITH NORMAL DECELERATION. THE ACFT EXITED THE RWY ON A HIGH SPEED TXWY AT APPROX 30 KTS. UPON CLEARING THE RWY THE FLTDECK BEGAN FILLING WITH SMOKE. THE SMOKE WAS NOT ELECTRICAL IN NATURE. THE COCKPIT DOOR WAS OPENED TO CHK FOR SMOKE IN CABIN. FA'S 'CHIMMED' THE FLTDECK AT THE SAME INSTANT. SMOKE BECAME THICKER IN THE FLTDECK AS WE ROLLED TO A STOP ON PARALLEL TXWY. COCKPIT WINDOWS WERE BOTH OPENED. AT THIS TIME CAPT AND MYSELF MADE THE DECISION TO EVACUATE THE ACFT. CAPT ORDERED 'EVACUATION CHKLIST.' I DONNED MY OXYGEN MASK AND WENT SPEAKER/HOT MIC AND BEGAN READING MY EVAC CHKLIST. WHEN CHKLISTS WERE COMPLETE AND ENGS WERE SHUTDOWN, THE SMOKE BEGAN SUBSIDING. CAPT AND MYSELF UNSTRAPED AND HELPED PASSENGERS EVACUATE THE ACFT. FWD SLIDES WERE DEPLOYED AND ALL PAX '48 AND CREW 5' EGRESSED THE ACFT. I WAS ORDERED BY CAPT TO GATHER ALL PASSENGERS OFF THE ACFTS LEFT FORWARD NOSE ABOUT 30 YARDS. ONLY POSSIBLE INJURIES AT THE SAME TIME WAS A SPRAINED ANKLE FROM ONE OF THE PASSENGERS. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THE AIRPLANE WAS A FOKKER 100 AND THE CAUSE OF THE EXPLOSIVE SOUND WAS THE LEFT PACK HEAT EXCHANGER RUPTURE. THE RPTR SAID THE PACK HEAT EXCHANGERS ARE LOCATED BENEATH THE COCKPIT FLOOR. THE RPTR SAID THE PACK COMPARTMENT WAS FILLED WITH HOT ENG BLEED AIR MIXING WITH OIL FROM THE AIR CYCLE MACHINE CAUSING THE COCKPIT AND CABIN SMOKE. THE RPTR SAID THE ACFT WAS EVACUATED ON THE GROUND WITH ONLY ONE PAX INCURRING A TWISTED ANKLE.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.

A fokker 100 on final approach at 400 ft experiences explosive sound below cockpit seats on ground, cockpit and cabin filled with smoke. Smoke caused by ruptured left pack head exchanger.