GulfstreamGuy From United States of America, joined Jul 1999, 646 posts, RR: 1 Posted (14 years 9 months 3 weeks 18 hours ago) and read 935 times:
I noticed when 737s (mainly just Southwest here in LIT) come in, on all the -200s, -300s, and -500s, the auxillary power unit in the tail cone section have only one exhaust "hole". However, on the -700s they have TWO openings. Anybody know the reason for this?
"If we couldn't laugh, we would all go insane. " -Jimmy Buffett
Jim From United States of America, joined exactly 15 years ago today! , 455 posts, RR: 1
Reply 1, posted (14 years 9 months 3 weeks 8 hours ago) and read 884 times:
It was explained to me that the second hole is used to ventilate and cool the APU compartment. Basically, the aft end of the tube is close enough to the exhaust to cause a venturi-effect, drawing air into the compartment. The forward end of the tube is next to the APU oil cooler, so air from the compartment is drawn across the oil cooler and exits overboard at the exhaust. I was told that the -700s & -800s have this.