747hogg
Topic Author
Posts: 168
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Backfire While Starting WN Jet At LAX Today

Thu Aug 24, 2006 3:24 pm

This must be a normal thing to the seasoned flyer, but it rocked my friggin' world! I was sitting next to #2 and as they were starting it up a big pop followed by a flash of flame shot out.. The A/C took on the smell of jet fuel for a few seconds as well. It kept right on spooling up to speed and no one said anything. For a split second I was honestly looking for an emergency door to head for. Normal? I've never seen this happen before.
 
ikramerica
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RE: Backfire While Starting WN Jet At LAX Today

Thu Aug 24, 2006 3:33 pm

Never seen it before in all my flights. I assume that since you went on your way, the ground crew and the flight crew didn't think it was a problem.

Sugar in the fuel tank? Potato in the tailpipe?  Wink
Of all the things to worry about... the Wookie has no pants.
 
fr8mech
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RE: Backfire While Starting WN Jet At LAX Today

Thu Aug 24, 2006 3:36 pm

Jet engines do not backfire, they compressor stall or surge. Was the flame out the front or rear? Out the front indicates a stall or surge, bad news. Out the back indicates an ignition system that was late igniting the fuel in the cans or some maintenance was done on the engine which required a wet motor and the engine wasn't cleared completely, no worries, probably.
When seconds count...the police are minutes away.
 
QXatFAT
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RE: Backfire While Starting WN Jet At LAX Today

Thu Aug 24, 2006 3:41 pm

Quoting Ikramerica (Reply 1):
Sugar in the fuel tank? Potato in the tailpipe?

Ahh my good ol high school years. But wait, that was just 4 years ago!

Quoting Fr8Mech (Reply 2):
Out the back indicates an ignition system that was late igniting the fuel in the cans or some maintenance was done on the engine which required a wet motor and the engine wasn't cleared completely, no worries, probably.

Wow thank you. I have been trying to figure out why that happend on one of my flights out of ABQ on WN one time. Never thought of this. Thank you for posting this answer!
Don't Tread On Me!
 
777wt
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RE: Backfire While Starting WN Jet At LAX Today

Thu Aug 24, 2006 7:45 pm

Quoting Fr8Mech (Reply 2):
or some maintenance was done on the engine which required a wet motor and the engine wasn't cleared completely

a FADEC or a FCU change which requires wet motoring to clear out the storage oil inside of them.
 
EMBQA
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RE: Backfire While Starting WN Jet At LAX Today

Thu Aug 24, 2006 8:32 pm

Quoting 747hogg (Thread starter):
Normal? I've never seen this happen before.

Very normal. It sounds like the crew did a residual start. That means the engine was too hot to do a standard start. They start the engine spooling with ignition off. This sucks in cool air and drops the ITT. You then introduce fuel and then a few seconds later add the ignition. Sometimes you get a surge at light off and a fuel small as the residual fuel burns off.
"It's not the size of the dog in the fight, but the size of the fight in the dog"
 
contrails
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 12:53 am

I saw this happen on an Eastern DC-9 at DCA not long before the carrier went under. It shot a flame back a good 10 feet, maybe more. I was on the Metro platform, probably a hundred feet or so away, when it happened. I'm glad nobody was behind it.

That's the only time I've seen something like that.
Flying Colors Forever!
 
luketenley
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 12:59 am

I saw this on a Delta MD80 a few months back. I assume it doesn't affect the engine or flight because it took off normal.
Pittsburgh International Airport lover
 
aogdesk
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 1:04 am

Watching an L1011 with RB211's was always a treat, seemed to happen alot, must've scared the daylights out of pax who happened to be checking out the tailpipe on engine start.
 
yhz78
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 1:24 am

Another good plane for this sort of thing is the F28's. Especially a kickstart flight in -15C conditions.
Canada Rocks! From the west coast to the best coast!
 
MD88Captain
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 1:25 am

It just isn't a big deal. At night, directly in back of an aircraft, one can look into the engine and see it light off. Sometimes it throws more flame than other times. And if there is residual flame in the engine you can get it to torch off. Again, no big deal. You will not even know about it in the cockpit.
 
barney captain
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 4:17 am

Quoting EMBQA (Reply 5):
It sounds like the crew did a residual start. That means the engine was too hot to do a standard start. They start the engine spooling with ignition off. This sucks in cool air and drops the ITT. You then introduce fuel and then a few seconds later add the ignition.

Good call EMB, but on the 737 at least, the ignition and fuel are both controlled by the start lever. There really isn't an effective way (short of pulling cb's) to separate the two. If we have high residual EGT, we simply motor the engine until it drops below 200 degrees, then light it off. You bring back fond memories though, the residual start you described is exactly the way we did it in the Metroliner....
Southeast Of Disorder
 
broke
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 5:13 am

Fire out of the tail pipe during starting of a turbine engine is called "torching". There maybe other reasons, but the most common cause is ignition of residual fuel that puddled in the tail pipe before the engine igniters (they are not spark plugs) are turned on. When the engine lights off, it can get the tailpipe hot enough to ignite the fuel and you get a flash of fire. It can happen on both jet engines and turboprop engines.
Torching has been experienced, at times, on an grander scale when the fuel shut off valve leaks and a considerable amount of fuel is in the turbine and tail pipe. This will cause a significant tongue of flame which can be very alarming to the causal observer. Usually continuing the engine start sequence will result in the flame going away due to airflow and the burning up of the residual fuel. Torching rarely causes any damage to the engine or airframe.
 
747hogg
Topic Author
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 7:18 am

Thanks, the puff of fire was out the back, but the A/C had a fuel smell for a few seconds as well.
 
ikramerica
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 9:18 am

Quoting 747hogg (Reply 13):
Thanks, the puff of fire was out the back, but the A/C had a fuel smell for a few seconds as well.

no expert, but smells usually come from incomplete combustion, and what is being described above would likely result in incomplete combustion of the "pooled" fuel, as it just gets hot enough to ignite, but not hot enough to burn it off completely.
Of all the things to worry about... the Wookie has no pants.
 
DLAgent
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 9:24 am

In the days of the L1011, we would experience that and it became a common occurance. They always had such a low whining sound, for about 45 seconds, it almost sounded as though they were hesitant to leave.
 
arluna
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 10:45 am

The combustion chamber drain valve could have been stuck allowing fuel to puddle in the bottom of the combustion chamber.

The Chinook that I crewed in Viet Nam had an APU that had an intermittantly sticky drain valve and it was a spectacular sight to see at night when a ten foot flame would shoot out the back of the aft pylon. We had a team of civilian contract maintenance folks from Lear Seigler who refused to get on the helicopter when they saw it, we left them on the ramp to find another way to their destination.

Jerry
 
steeler83
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 11:00 am

Quoting Ikramerica (Reply 1):
Potato in the tailpipe?

*mocking* I'm not falling for the banana in the tailpipe?

-Eddie Murphy, Beverly Hills Cop  Smile

Now that is what I'd call one baked  flamed potato
Do not bring stranger girt into your room. The stranger girt is dangerous, it will hurt your life.
 
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HAWK21M
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 11:08 am

Quoting Fr8Mech (Reply 2):
Out the back indicates an ignition system that was late igniting the fuel in the cans or some maintenance was done on the engine which required a wet motor and the engine wasn't cleared completely, no worries, probably.

Also can be contributed by what RPM did the Pilot Introduce Fuel.Was it earlier than required.

Quoting Broke (Reply 12):
Fire out of the tail pipe during starting of a turbine engine is called "torching"


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MEL
I may not win often, but I damn well never lose!!! ;)
 
Gilligan
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 11:47 am

Memories...dah dah dah dah dah dah......

I remember pushing out the silver anniversary bird and watching the number 1 smoke like a barbeque. Called the cpt on the headset and reported the smoke. He said, ok, how this? About then a tongue of flame shot out the rear end of the engine almost all the way back to the tail accompanied but a large "TONK". Before we got to the disconnect point the cpt asked if we could drag him back to the gate, somebody wanted off. Somebody turned into about 6 or 7.

Working on the ramp for CO I got completely used to seeing the EMB's torch on a regular basis. Especially when it was cold outside. Since the tailpipes are in the back out of view, never had to drag one back but it's a pretty impressive sight.
Warm winds blowing, heating blue skies, and a road that goes forever, I'm going to Texas!
 
LPLAspotter
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 11:28 pm

Quoting Aogdesk (Reply 8):
Watching an L1011 with RB211's was always a treat, seemed to happen alot, must've scared the daylights out of pax who happened to be checking out the tailpipe on engine start.

Man those things would pour out smoke. Even the new ones did that. One time on a TWA L1011 they made an announcement that this would happen so nobody would freak out.

LPLAspotter
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OPNLguy
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RE: Backfire While Starting WN Jet At LAX Today

Fri Aug 25, 2006 11:43 pm

Quoting LPLAspotter (Reply 20):
Man those things would pour out smoke. Even the new ones did that. One time on a TWA L1011 they made an announcement that this would happen so nobody would freak out.

If memory serves, Delta had an L10 on the taxiway at DFW some years ago, in queue for departure and started one (either #1 or #3) that had been shut down to conserve fuel. Typical RB211 smoke/torch, and someone indeed freaked and commenced a passenger-initiation evacuation. I don't recall how many people joined him/her (it was several) but it's easy to understand the human nature aspect of bailing out first and asking questions later.
ALL views, opinions expressed are mine ONLY and are NOT representative of those shared by Southwest Airlines Co.
 
airfoilsguy
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RE: Backfire While Starting WN Jet At LAX Today

Sat Aug 26, 2006 12:12 am

was it sorta like this?





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LPLAspotter
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RE: Backfire While Starting WN Jet At LAX Today

Sat Aug 26, 2006 1:30 am

There's a great video on flightlevel350.net of a IB 747 experiencing a compressor stall on takeoff from ORD. Here it is: http://www.flightlevel350.com/Aircra...ne_Iberia_Aviation_Video-1652.html

LPLAspotter
Nuke the Gay Wales for Christ
 
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HAWK21M
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RE: Backfire While Starting WN Jet At LAX Today

Sat Aug 26, 2006 5:03 pm

Quoting Airfoilsguy (Reply 22):
was it sorta like this

Wonder what the EGT was like  Smile
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Lucky42
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RE: Backfire While Starting WN Jet At LAX Today

Sat Aug 26, 2006 5:19 pm

It is quite common on the DC-9/MD-80 aircraft. You open the start valve and motor the engine then throw the fuel lever and forget that you didn't turn the ignition on and before even thinking about it you reach up and turn on the ignition and BAM all that residual fuel lights off and you have a nice big flame behind you. This happens mostly to MX but I have seen a few pilots do it over the years....Thats why it pays to use a checklist.
 
777wt
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RE: Backfire While Starting WN Jet At LAX Today

Sat Aug 26, 2006 7:42 pm

Quoting Gilligan (Reply 19):
Working on the ramp for CO I got completely used to seeing the EMB's torch on a regular basis. Especially when it was cold outside. Since the tailpipes are in the back out of view, never had to drag one back but it's a pretty impressive sight.

I was waiting to watch an ERJ-145 shoot flames out the back once. It never occured tho.
It was a airstart due to a deferred APU. Engine attempted to start and resulted in a hung start on #2. Again and a crapload of fuel sprayed out the back with no flame.

So one of the techs here comes out and told the ramp to disconnect the airstart cart. Then the tech starts up the APU and started eng #2 from the APU with no problems. I think it was deffered for a APU GEN problem.
 
DTWAGENT
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RE: Backfire While Starting WN Jet At LAX Today

Sat Aug 26, 2006 10:39 pm

I've seen it happen and the first time I left a mess in my pants. After that I was ok with it. Of course I was 7 yrs old when I first saw this happen. And yes it was on the L-1011 in DTW.

Chuck
 
jeb94
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RE: Backfire While Starting WN Jet At LAX Today

Sun Aug 27, 2006 3:54 pm

Reminds me of a night on the ramp in MKE. A DC9-30 had just pushed off and was starting up. A lot of vapor poured out of the #2 engine followed by a huge fireball that lit up everything. The captain brought it back to the gate claiming some sort of ignition problem. MX had no problems starting it while following the checklist. I just recently saw something similar on an MD80 in LAS. A mechanic forgot the ignition switch and the #1 engine spit a quick 10 foot flame rather than a huge fireball this time. JT8Ds both large and small thud when they start.

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