Why the whoop whoop noise on NWA's DC-9's

[PhatAJ2008]

On another note, I read a memo from the CEO of US Air to some ground guys at Philly. They had a -767 going to Europe, and the tugs were broken at 2am. So, they got a bunch of ground guys and physically pushed back the -767 out of the gate!

Must have been interesting to see.

 

[PA31Ho]

why would i hear it through the headsets?

 

[PCL_128]

What you're hearing is the igniters. You'll notice that you only hear it when the PA is being used by the FAs. If they stop using the speakers, then the noise stops. It's due to the low shielding that the speaker wires have, and they pick up the distortion from the high-power electricity coming from the igniter boxes. I used to hear the same thing in the BE1900 when I was wearing a headset during engine starts.

 

[Gorilla]

It is the igniters, not the hydraulic system. DC-9 igniters are badly shielded and bleed through pretty much any headset cable in the airplane. IIRC it is a big capacitor which is charged prior to delivering its jolt through the combustion chamber. Think of a camera strobe charging prior to its flash... same deal.

 

[GINCHBLASTER]

What you're hearing is the igniters. You'll notice that you only hear it when the PA is being used by the FAs. If they stop using the speakers, then the noise stops. It's due to the low shielding that the speaker wires have, and they pick up the distortion from the high-power electricity coming from the igniter boxes. I used to hear the same thing in the BE1900 when I was paying to wear a headset during engine starts.

Fixed it for you.

 

[PCL_128]

Fixed it for you.

Thanks. Real clever.

 

[skydash]

What you are hearing is......The Devil

 

[flyguyMN]

Why would you be starting engines *after* powerback? Seems a powerback would be much more sucessful with the engines running.

If you go to Flightlevel350.com and look at the DC9 videos, in two of them you can clearly hear the "Whoop Whoop" noise before powerback and once after powerback.

 

[flyguyMN]

What you're hearing is the igniters. You'll notice that you only hear it when the PA is being used by the FAs. If they stop using the speakers, then the noise stops. It's due to the low shielding that the speaker wires have, and they pick up the distortion from the high-power electricity coming from the igniter boxes. I used to hear the same thing in the BE1900 when I was wearing a headset during engine starts.

On numerous occasions, the FA's were not using the PA nor could I tell the PA was on. But when they due use them, the noise is more prevelant.

 

[flyguyMN]

What you are hearing is......The Devil

And how would you know what the Devil sounds like!!! Get a life and post something that is relevant to the topic being discussed.

 

[Green Banana]

ya, like all the guessing about stuff in this link is not totally useless. By the way, I think it is the coffee heating element charging up.

 

[cezzna]

What you are hearing is the capital disintegration valve cycling. As soon as the engine is started, or the hydraulic fluid starts to flow, the capital disintegration valve starts to move any liquid assets. These liquid assets then vanish into thin air after passing through the CDV. After the CDV valve stops cycling the BRV(the bankruptcy reorganization valve) starts to cylce. You will know the BRV valve has stopped cycling when you are on a newer airplane or a greyhound bus.

 

[AAflyer]

Whatever you do, DO NOT tape it and play it backwards!!!!!!!


VVTTVVTT...Pilots get paid too much.....
VVTTVVTT...Pilots get paid too much......


AA

 

[mattpilot]

I always hear it on Delta's 757. ALways sounds like some mechanic is screwing on some plates in the last minute

 

[HawkerF/O]

These guys are just playing with you. It's the Kanooter Valve cycling K9P (A very harsh and corrsive anti-icing chemical) through the engines to ensure no jet/prop wash was accidentally injested into the engines when it was being cleaned. The Carburator injects the fuel through a turbo charged supercharger, which has a exhaust outlet at the front of the engine. That exhaust outlet also acts as reverse thrust. When the reversers are activated, the engine stops, then changes direction, and the exhaust is what blows against the fan blades to stop it from turning 1 direction, then backing up in the other direction to provide you with good 'ol reverse thrust. It's really a neat process to watch, but you have to be quick because it all happens so fast.

Watch some of the made for TV movies and you'll learn a lot about the airlines and how airlines are flown and what the noises and sounds are. I can remember this 1 movie with Robert Urich in it. GREAT TV movie. He was the maverick pilot that did things his way and not by the book. As he was doing he pre-flight checks, his Chief Pilot I guess came up to the flight deck and told him he wanted him to "fly by wire" tonight. I didn't knwo he had a choice. That was cool. I guess if he didn't fly by wire, when he turned the system off, a mechanical linkage would appear in place of the fiber optics and actuators. Cool. But that is not even the best part. Listen up, cause this might just save your life:
Same movie. A small fire in the cabin broke out. The F/As are trained not to use the fire extinguisher right next to her, but instead, they are to call the pilot right away and have them put the fire out. That's right, as soon as those pilots got the call, they started looking for and then found the "dousers". They hit the dousers and the fire was out out right away, so don;t forget to check douser pressure before each take-off.

Co-Pilot: Fly by Wire Master Control Switch
Pilot: OFF you maggot co-pilot. When I was in NAM we didn't have that dang Fly by wire, we flew by our A$$ you buzzard ba$tard!! Next!!
Co-Pilot: Douser System Pressure Check
Pilot: System checks, armed, pressures in the green.
Co-Pilot: Seat 1A Douser
Pilot: checked
Co-Pilot: Seat 1B douser
Pilot: Check

ETC, ETC, ETC. YOu get the picture.