The air goes out the outflow valve anyway pressurized or non-pressurized. Depressurizing and opening the ram air valve results in a faster turnover rate of air in the cabin for smoke removal or there would be no benefit to doing it. If necessary the checklists also call for opening the flight deck windows for even more airflow.
Someone mentioned a fire at 30W. Pretty simple slate of choices if you ask me. Ditch or burn!
Discovery Mayday
Moderators: lilfssister, North Shore, sky's the limit, sepia, Sulako, I WAS Birddog
I remember te accident and if memory serves me correct, the crew attempted several resets of the circuit breakers to the flushing motors. This prompted research into the hazards of reseting C/B's and TC's recomendation to not reset any one that pops unless safety of flight is an issue and then only one reset.
As far as oxygen at altitude is concerned, the percentage of oxygen is the atmosphere remains at a constant 21%, it is the total pressure that changes. It is like comparing 21% of one dollar as opposed to 21% of one cent. The ratio is the same but the total value is less. As far as dumping the cabin is concerned, remember one thig and it is very imortant. GET YOUR OXYGEN MASK AND SMOKE GOGGLES ON, FAST. The crews oxygen system is seperate from the passengers system so you are not dumping all the cabin masks.
Also, know where the outflow valve and dump valve is located. If the dump valve is in the forward pressure bulkhead, dumping the cabin will bring the smoke forward. If the outflow valve in in the rear pressure bulkhead, raising the cabin altitude to maximum will open the outflow valve and the smoke will follow. Turning the bleed air switches off will cause the cabin to climb at the normal leak rate. The outflow valve will close to attempt to hold pressurization and the smoke will remain. If the fire is electrical, turn off power to that bus. What happens is that the switch the pilot has access to is usually the control circuit. This will provide a small amperage current to a large coil in a relay that will create the electromagnet heavy duty switch that actually connects the high current flow to heavy draw items. By reseting a c/b, you usually weld the contacts of the relays closed and current flows unless a "hail mary" current limiter or heavy duty circuit breaker breaks the ccircuit and stops the flow of current. If memory serves me, this is what was determined to be the problem on this flight.
As far as oxygen at altitude is concerned, the percentage of oxygen is the atmosphere remains at a constant 21%, it is the total pressure that changes. It is like comparing 21% of one dollar as opposed to 21% of one cent. The ratio is the same but the total value is less. As far as dumping the cabin is concerned, remember one thig and it is very imortant. GET YOUR OXYGEN MASK AND SMOKE GOGGLES ON, FAST. The crews oxygen system is seperate from the passengers system so you are not dumping all the cabin masks.
Also, know where the outflow valve and dump valve is located. If the dump valve is in the forward pressure bulkhead, dumping the cabin will bring the smoke forward. If the outflow valve in in the rear pressure bulkhead, raising the cabin altitude to maximum will open the outflow valve and the smoke will follow. Turning the bleed air switches off will cause the cabin to climb at the normal leak rate. The outflow valve will close to attempt to hold pressurization and the smoke will remain. If the fire is electrical, turn off power to that bus. What happens is that the switch the pilot has access to is usually the control circuit. This will provide a small amperage current to a large coil in a relay that will create the electromagnet heavy duty switch that actually connects the high current flow to heavy draw items. By reseting a c/b, you usually weld the contacts of the relays closed and current flows unless a "hail mary" current limiter or heavy duty circuit breaker breaks the ccircuit and stops the flow of current. If memory serves me, this is what was determined to be the problem on this flight.
The average pilot, despite the somewhat swaggering exterior, is very much capable of such feelings as love, affection, intimacy and caring.
These feelings just don't involve anyone else.
These feelings just don't involve anyone else.
sadly, one of those who perished in this accident was one of the finest singer/songwriters canada has ever produced.....stan rogers
rise again......
http://www.stanrogers.net/
http://en.wikipedia.org/wiki/Stan_Rogers
rise again......
http://www.stanrogers.net/
http://en.wikipedia.org/wiki/Stan_Rogers
"Honi soit qui mal y pense"
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YYZ_Instructor
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If my memory serves me correctly the procedures for smoke in the cabin does not mean open the outflow valves, only if it restricts the pilots from flying duties. Cockpits on airliners are equiped with quick donning masks providing 100% oxygen with the ability to give full flow or only when breathed depending on the circumstances. By dumping the cabin at a high altitude the passenger masks are useless, they are diluted with cabin air anyway, so they would be breathing smoke no matter what for about 15min, then full smoke. The passenger mask oxygen is of the chemical reaction type where oxygen is produced via heat, pilots on the other hand have a seperate compressed oxygen system in the cockpit with 100% oxygen. By dumping the cabin you would minimize the fire for a while, but descent would be imminent and you would be abck to the same situation you started with. Therefore all electrics off and hopefully a cabin attendant would use their emergency masks and get to the place with an extinguisher if possible while preparing for immediate landing (I would never dump fuel in that situation.....landing is more important than saving the structure.
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Siddley Hawker
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Oldtimer, you've brought up a subject that I've never seen addressed properly in this accident, namely how many times can you reset a non-essential circuit breaker in flight. Now first off, I know very little about a DC-9, but I assume the flush motors were on a non-essential DC buss. Once that breaker popped, that should have been it, no attempt at a reset. Our checklist on the F-27 read do not attempt to reset any non-essential circuit breaker in flight. We were allowed one reset of an essential breaker, and then only if a situation arose that presented a greater danger to the flight than the loss of that system.
The only circuit breakers that should be reset in flight are those that would be CRITICAL to the remainder of the flight. Generally if a CB pops out it is mad at the world. Never screw with a mad CB. I can think of only a few rare instances on the many types I have flown where I would have vilolated this general principle.
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Siddley Hawker
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We did our recurrent on the F-27 at USAir and the Gulfstream and Hawker at Flight Safety. Their policy was as I stated in my earlier post, no reset of a non-essential CB in flight, and one reset of an essential CB, but only if reinstatement of the affected system became critical to the safety of the flight, as pushyboss stated. We incorporated that procedure into our checklists in the early 1970's.
We had the same type flush motors on our F-27 as that DC-9 did, Borg-Warner model something or other if I remember right. After the DC-9 accident, Transport Canada issued a service letter with a recommendation that on the initial check of the aircraft in the morning, the toilet was to be flushed and the the operation of the motor was to be monitored for any unusual noise.
We had the same type flush motors on our F-27 as that DC-9 did, Borg-Warner model something or other if I remember right. After the DC-9 accident, Transport Canada issued a service letter with a recommendation that on the initial check of the aircraft in the morning, the toilet was to be flushed and the the operation of the motor was to be monitored for any unusual noise.
Oldtimer and Hawker Sid,
I have often used this accident in a training scenario for new crew members. The c/b multi reset attempt often gets lost in the other stuff around this accident. Over the years that aspect of the events has been shunted aside it seems.
Shortly after the accident I found myself down in the States on a type course and came into contact with some folks that manufacture aircraft c/b's. I had already been of the camp that c/b's once tripped should be left unless that componant/system was absolutely critical to getting the aircraft on the ground safely. After talking to these folks however I became even more adamant in that belief
What a lot of folks don't understand is that once a c/b has tripped, it has been traumatized, and has done what it was designed to do. The manufacture assures that it is designed to do it once but does not assure anything after that. Once a pilot starts resetting it, all bets are off.
So you have to ask yourself, how important is that item to me for the rest of this flight vs what are the consequences if that already traumatized c/b doesn't work the next time and allows electrical energy to flow when or where I don't want it?
I have often used this accident in a training scenario for new crew members. The c/b multi reset attempt often gets lost in the other stuff around this accident. Over the years that aspect of the events has been shunted aside it seems.
Shortly after the accident I found myself down in the States on a type course and came into contact with some folks that manufacture aircraft c/b's. I had already been of the camp that c/b's once tripped should be left unless that componant/system was absolutely critical to getting the aircraft on the ground safely. After talking to these folks however I became even more adamant in that belief
What a lot of folks don't understand is that once a c/b has tripped, it has been traumatized, and has done what it was designed to do. The manufacture assures that it is designed to do it once but does not assure anything after that. Once a pilot starts resetting it, all bets are off.
So you have to ask yourself, how important is that item to me for the rest of this flight vs what are the consequences if that already traumatized c/b doesn't work the next time and allows electrical energy to flow when or where I don't want it?
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Beater driver
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linecrew
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- Location: On final so get off the damn runway!
I never did see the documentary but did they bother to go into how this same DC-9 had lost it's entire tailcone a few month prior to the accident flight?
I have it on good authority that there were electrical probalems stemming from the repair done when reinstalling a tailcone which lead to the fire. The NTSB lists the source of the fire as "unknown" in their investigation.
I have it on good authority that there were electrical probalems stemming from the repair done when reinstalling a tailcone which lead to the fire. The NTSB lists the source of the fire as "unknown" in their investigation.
