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rrietz
User Rank
Iron
Re: Vents can't be skipped
rrietz   7/18/2013 11:04:38 AM
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One wonders about why maintenance workers were working 20 hour days.  That is just flat unsafe.

Also, about the person breaking a leg walking on a fuel spill...  That stuff is very slick.

OLD_CURMUDGEON
User Rank
Platinum
Clogged lines.... an interesting point!
OLD_CURMUDGEON   7/18/2013 10:51:07 AM
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This blog brings up several thoughts.  In the northern climes, the vent stack for the DWV plumbing in a building is usually a minimum of 4" nominal dia. pipe.  This has been mandated for decades to eliminate the probability that the vent line will become frozen over w/ ice, since the water vapor escaping is warm, meeting the cold ambient temps.  Here in the south, these vent lines are usually 2" pipe since the frequency of extreme freezing temps is non-existent.  However, because of the almost never-ending "summer" season, air conditioning is a constant commodity.  And, with A/C units there IS condensation which must be piped away from the evaporator source.  Add to that, our friendly little "lizards" which really enjoy traveling up these tubes, only to get stuck & die, and now you have a blocked drain line.  While this is usually NEVER a life-threatening event, if the evaporator is mounted in the crawl space attic area, an overflowing drip pan will cause stain damage to one's ceiling.  NOT GOOD!

So, my question becomes, WHY can't this drain line be a larger pipe size so that it will be less likely to get clogged?  And, a similar question applies to the vent on the fuel tank of the airplane.  Why can't the designers make the vent pipe a larger pipe size to accommodate ice build-up, especially knowing full well that airplanes travel at altitudes in which the air is cold, at freezing or below, even in the warm months of the year?  This seems like a no-brainer, but there MUST be a legitimate reason other than economics. 

btlbcc
User Rank
Gold
Vacuum in fuel tank
btlbcc   7/18/2013 10:22:15 AM
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I once had an old Mercedes-Benz 190D car (which I bought for $60) that burned almost more motor oil than diesel fuel (about a quart every 30 miles).  Otherwise a great car.  But at some point in the car's history, the vent hole in the fuel filler cap had gotten plugged.  The Bosch fuel injection pump is a no-nonsense piece of equipment, and it managed to collapse the (steel) fuel tank so that it's capacity was halved, and the fuel gauge didn't read correctly.  I doubt that a typical gasoline car fuel pump could manage that feat, but with the advent of fuel injection, I am not so sure...

bob from maine
User Rank
Platinum
Re: Fuel Systems
bob from maine   7/18/2013 10:11:03 AM
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As a 15 year old student pilot I was frequently 'tested' to be sure I paid suitable attention to all aspects of flying. My instructor would occasionally shut off the fuel at the selector valve (which was between the seats and not in my field of view). The engine would lose power and then die. I had to do the standard 'engine-out' routine, determine a suitable landing spot, wind direction, speed, identify local hazards, prepare to notify the local tower that I was landing. As soon as I had completed all the necessary tasks he would turn the fuel back on and we would continue - or not, once. You ignore anomolies at your peril. The fan is not the most important thing on an aircraft, the pilot is. Good story!

WA4WZP
User Rank
Iron
Re: Close attention pays off
WA4WZP   7/18/2013 9:34:41 AM
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Obviously this writer is not a pilot...or maybe a pilot that has never had an engine stop in mid-flight. I have! An automobile tire exploding (I have), even in busy traffic, is not even in the same 'world' as an airplane engine stopping in flight, or on take off, or on landing!

AREV
User Rank
Platinum
Re: Close attention pays off
AREV   7/18/2013 9:24:16 AM
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After 11 years my my Walker mower w/ Kawasaki engine would start, perform okay for about 2 minutes, die and require about 5 minutes, repeat. Luckily my dealer knew that there was a vent in a brass plug that could not be seen through even when clean. The instructions were remove the plug, soak it in gas over night, blow on it  and run the engine another 11 year bnd hope we remember how to fix it again. That's a lawn mower. I would think an air plane would engineer that issue out or have a sensor to detect vaccuum or pressure in the tank.

j-allen
User Rank
Gold
Re: Close attention pays off
j-allen   7/18/2013 9:16:57 AM
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A good friend of mine also had a mud dauber clog in the pitot tube of the air speed indicator.  (I think it was on a Curtiss Robin.)  Fortunately he was a skillful enough pilor to make a "seat of the pants" landing but it was scary. 

 

Another critter that causes clogs is the spider that forms cotton ball like webs inside small openings.  They frequently block up the venturi tubes of outdoor gas grills.

jfowkes
User Rank
Iron
Re: Close attention pays off
jfowkes   7/18/2013 9:16:31 AM
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@far911 "Cars are more forgiving in this regard since there's no danger of them falling off the sky. The consequences of not paying attention to car maintenance are much less severe."

That's not necessarily true. If the engine had stopped in mid-air, the pilot would (almost certainly, unless they were very unlucky or were flying too low) have time to glide to a suitable site for a forced landing.

Conversely, imagine a badly maintained tyre exploding on a busy, wet motorway. You only have seconds to keep control of the vehicle before you might hit something solid.

Battar
User Rank
Platinum
Wasps brought down 757
Battar   7/18/2013 9:03:04 AM
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Check this link:

http://en.wikipedia.org/wiki/Birgenair_Flight_301

A Turkish Boeing 757 was brought down by wasps in the speed sensing pitot tube, with the loss of all 189 people on board.

mrmikel
User Rank
Iron
Re: Close attention pays off
mrmikel   7/18/2013 9:01:43 AM
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A great reminder that routine checks can be anything but routine.  Reminds me of Sherlock Holmes...you see but you do not observe.


The author did both and prevented a crash.

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