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Jungle Jet (EMB-145); Pulsing Apu?  
User currently offlineSunken_Lunken From United States of America, joined Jul 2001, 87 posts, RR: 0
Posted (11 years 10 months 3 days ago) and read 3139 times:

I was a passenger on an EMB-145 a while ago. When we exited the plane at the gate, I heard a recurring noise that sounded like the APU was cycling on and off. There were several seconds between cycles, but it seemed pretty frequent.

Can the APU on this plane be set to cycle on and off like this? If so, what is the reason?

6 replies: All unread, jump to last
 
User currently offlineAA777-200 From United States of America, joined Jul 1999, 322 posts, RR: 2
Reply 1, posted (11 years 10 months 3 days ago) and read 3104 times:

What you are hearing is the heat exchangers/air packs down under the wings. They are in an annoying cycle that goes then stops for a few seconds and comes back on. It is a high pitched noise and gets annoying when your working around the aircraft.

User currently offlineSunken_Lunken From United States of America, joined Jul 2001, 87 posts, RR: 0
Reply 2, posted (11 years 10 months 2 days 23 hours ago) and read 3085 times:

Thanks for the info AA777-200.

I was only around the plane for a minute or 2. I can imagine how annoying that would be hearing it for longer periods several times a day.


User currently offlineJetdoctor From United Kingdom, joined Aug 2001, 257 posts, RR: 0
Reply 3, posted (11 years 10 months 2 days 12 hours ago) and read 3025 times:

Wow you were actually on a 145 with a working APU???

AA777 is correct in stating what you proabaly heard. When the packs are first selected, they cycle up and down until stabilized. Once they are going for a few minutes, they are ok, unless the cabin/cockpit temp is changed, or they are reset.

And AA777, you should be wearing your company appointed orange headgear!!
Remember noise is the invisible hazard!!

RT



Break ground, and head into the wind. Don't break wind and head into the ground.
User currently offlineRamper@iah From United States of America, joined Dec 2001, 240 posts, RR: 1
Reply 4, posted (11 years 10 months 2 days ago) and read 2982 times:

Jetdoctor,

Out of curiosity, are the APUs installed on the Embraers at your company considered unreliable? We use the Sustrand C-14 and C-11 models, and have had very little trouble with them. The C-14s tend to get hot during engine starts, but other than that, they work like a charm.


User currently offlineJetdoctor From United Kingdom, joined Aug 2001, 257 posts, RR: 0
Reply 5, posted (11 years 10 months 1 day 9 hours ago) and read 2944 times:

Ramper@iah

Yes, we also use the Sundstrand C11 and C14 APU's on our fleet. Through my experience on aircraft, they seem to be a very unreliable unit, as compared to say a Garrett APU. We are seeing a lot of improvement with the C14, primarily because it is a FADEC controlled unit, but we still have uncommanded inflight shutdowns and numerous APU fails.

Now with winter coming, we get to look forward to glycol ingestion, which really isn't the APU's fault. More like an intake design problem, and a lack of knowledge of the deicing crews (who seem to like to spray glycol directly into the intake)

I am assuming you work for ConEx, and maybe your operating climate is better suited for the APU. Just a thought.

Regards
RT




Break ground, and head into the wind. Don't break wind and head into the ground.
User currently offlineAA777-200 From United States of America, joined Jul 1999, 322 posts, RR: 2
Reply 6, posted (11 years 10 months 13 hours ago) and read 2894 times:

Soo that means when I deice this winter and fill up the APU with glycol you get to fix it huh?  Acting devilish Yeah yeah I usually wear my nice bright orange ears...but sometimes I forget to grab them ( hope them auditors dont come looking for me)
Brad


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