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notaxonrotax
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Why No Pitot Covers On Airliners?

Fri Jul 22, 2011 5:12 pm

Hi,

my question is rather simple:

Why don´t I see the "remove before flight" covers on Airliners during prolonged lay-overs?

I can understand that you won´t bother with them during short turn around's, but what if an aircraft remains on the apron for a good few hours, or even a night? Wouldn´t it be prudent to cover them as much as you can?

I´m only a private pilot, and I always get drilled about covering the pitot, even only for short times!

Thanks,

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PGNCS
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RE: Why No Pitot Covers On Airliners?

Fri Jul 22, 2011 5:27 pm

They are often impossible for the crew to remove, are sometimes tough for the crew to see, and the hazards of taking off with them in place are greater than the hazards of leaving them uncovered. Further, most airliners typically sit for hours rather than days like you sometimes see in GA; when they are at a maintenance station for a prolonged period they sometimes will be covered. Different airlines have different policies.
 
fuelfool
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RE: Why No Pitot Covers On Airliners?

Fri Jul 22, 2011 7:32 pm

I work at a FX hub. If planes are going to sit for more than a certain amount of time, 12 hours I believe, engine covers and pitot tube covers are used. They are very common over the weekend.
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474218
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RE: Why No Pitot Covers On Airliners?

Fri Jul 22, 2011 7:43 pm

Remember the pitot tuble are heated. So they must be allowed to cool before the covers can be installed. So as 'fuelfool' there is a certain period of time that the aircraft will be inoperative before the covers are installed.
 
EMBQA
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RE: Why No Pitot Covers On Airliners?

Fri Jul 22, 2011 7:48 pm

Quoting 474218 (Reply 3):

They are only heated when in the air and cool quite quickly. The biggest reason you don't see them in the field is safety. The results if left on would be horrid.. and most all airlines I've dealt with the the installation of the covers is RII and would require an RII qualified mechanic or inspector present when removed. The manpower required would be huge.
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PGNCS
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RE: Why No Pitot Covers On Airliners?

Fri Jul 22, 2011 8:41 pm

Quoting EMBQA (Reply 4):
They are only heated when in the air and cool quite quickly.

Not universally correct (MD-80, B-737, etc.)
 
planenut767
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RE: Why No Pitot Covers On Airliners?

Sat Jul 23, 2011 2:05 pm

The only time I've seen them used where I work, is when they do an aircraft wash and that is done to keep any water/cleaning solution out of the pitot static lines so nothing freezes later on at altitude and damages the system. Otherwise the other posters are right about the reasons you don't see them placed on there due to time and accessability.
 
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HAWK21M
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RE: Why No Pitot Covers On Airliners?

Sat Jul 23, 2011 7:10 pm

Quoting fuelfool (Reply 2):
I work at a FX hub. If planes are going to sit for more than a certain amount of time, 12 hours I believe, engine covers and pitot tube covers are used. They are very common over the weekend.

Thats how its out here. > 2hrs halt or towing for Maintenance.....The L/G pins are installed with pitot covers in place.
Exceeding 8 hrs halt the Engine covers go on.
If the Area is Insect prone then > 2hrs halt need the pitot covers to be placed on.
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B6JFKH81
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RE: Why No Pitot Covers On Airliners?

Sat Jul 23, 2011 7:41 pm

Quoting notaxonrotax (Thread starter):
Why don´t I see the "remove before flight" covers on Airliners during prolonged lay-overs?

Aircraft get delivered with full kits. For our A320's, the kits come in silver metal suitcases, our E190's come in larger blue bags because of the foam plugs for the engine exhausts. The kits will typically consist of covers for the various probes, ice detectors, engine intake and exhaust, and APU exhaust. I also believe our A320 kits come with the fuel tester tool but we have to remove them as we are not a DG carrier so in order for us to COMAT them, we can't have the fuel test tools in there with the potential of having left-over fuel. There are other covers as well, but they may not apply to all aircraft. These kits were removed off our aircraft as standard equipment for weight savings (I know, I know, really stupid move, but I didn't make that decision...I did fight it though!).

Now, we DO cover things up during an RON if weather is going to be an issue. For example, if we have an aircraft that is going to be touching down in a city where there is supposed to be snow or ice overnight, maybe a dust storm, they get covered up. But what you have to remember is that planes are on the move A LOT. In a 24 hour day, it is actually common for a plane to be on the move over 12 hours. When that plane settles down for the evening, a lot of times MX crews are working on the plane. Now, if a plane is in a hangar, it is REQUIRED (by our airline) for engine covers to go on unless work is being performed on the engine or there is an engine change. Why? Because if the foam system goes off, it prevents the foam from going in the engine which would require an engine change. 2 engines per plane, 3 planes in the hangar, 6 engines would need to be changed which would have impacts on the operational schedule.

GA aircraft have the potential for being on the ground for days even weeks at a time before being flown again, and are also on ramps where there isn't that much activity compared to a terminal ramp where you have baggage carts, belt loaders, maintenance trucks, or even hangars where you also have a lot of hustle around (animals don't like hustle). Smaller planes have a higher risk of having birds nesting in various holes, insects getting in a building nests, and stuff being exposed to weather for a longer period of time.

Hope that helps!

~H81
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JT8DJET
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RE: Why No Pitot Covers On Airliners?

Sun Jul 24, 2011 2:10 am

Come to SDF, and you'll see plenty of brown tail with them on.

Any aircraft with a 6 hour or more layover, will have them installed.

We install them within 10-15 min after block-in, and they stay on until the flight crew shows up for preflight, or 1 hour before departure.
 
B777LRF
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RE: Why No Pitot Covers On Airliners?

Sun Jul 24, 2011 8:37 am

We found out the hard way it's a good idea to fit engine blanks during long stops. Being an integrator, our aircraft spends a very large part of the day sitting on the ground, quite often from 0900 to 2000. We experienced several engine vibration issues on one fleet. The root cause was traced to wear caused by windmilling, as the engine is not being lubricated when it is windmilling. We started fitting blanks and the problem went away.

Pitot covers are only fitted for longer (week-end) stops, or in case of specific weather conditions.

With our lot engine blanks and pitot covers may be fitted by specifically trained staff, and it does not require a certified aircraft mechanic or B2 inspector to verify either fitting or removal. It's hardly rocket science, and 2 blanks and 2 covers are pretty easy to count.

I would suggest the OP had a look around the cargo apron of various airports, and look for something either Yellow, Brown or Purple. Should be able to notice they've quite often fitted with covers. Unlike the chancers over at the passenger side of the business, who are too cheap to fit them  
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HAWK21M
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RE: Why No Pitot Covers On Airliners?

Sun Jul 24, 2011 10:26 am

Quoting B777LRF (Reply 10):
The root cause was traced to wear caused by windmilling, as the engine is not being lubricated when it is windmilling. We started fitting blanks and the problem went away.

Engine Blanks/covers help in high wind conditions to reduce wear caused by continous windmilling.
On the Pitot covers,In high winds they tend to get blown away hence velcroded ones are preffered.Removal is easier as there is an extended length lanyard used for pulling them off the pitot tubes.
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stratosphere
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RE: Why No Pitot Covers On Airliners?

Tue Jul 26, 2011 2:22 am

Quoting EMBQA (Reply 4):
The biggest reason you don't see them in the field is safety. The results if left on would be horrid.. and most all airlines I've dealt with the the installation of the covers is RII and would require an RII qualified mechanic or inspector present when removed.

Actually I have never seen that as an RII item and I dont know why it would be. Most passenger airlines you dont see it like has been said here if an a/c is going to sit for 12 or more hours some airlines do it but it requires a log book entry just like gear pins would. In the freight world I have seen airplanes sit over the weekend and I remember out west I think it was fresno we had a bad problem with mud dawbers building nests in the pitot tubes.
 
RCnoob
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RE: Why No Pitot Covers On Airliners?

Tue Jul 26, 2011 3:37 am

Yes, pitot covers could lead to disaster if not removed. In 1996 an Air Peru 757 had a CFIT disaster due to the static ports being covered. The aircraft had been washed that day, and the mechanics did covered them with tape. The mechanics did not remove the tape, and nobody caught it on walkaround. The aircraft was photographed on the bottom of the Pacific Ocean with tape still in place.

The automated Ground Proximity Warning System gave a variety of warnings, some correct and others not. The crew struggled to figure out their situation, but ultimately flew into the Pacific Ocean, still believing they were 9,700 feet Above Ground Level (Walters & Sumwalt, 2000, chap. 4, "A Tale of Two Tragedies).

Excerpt from a book I'm writing on art and science in flying.
 
dhawald3
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RE: Why No Pitot Covers On Airliners?

Tue Jul 26, 2011 4:28 am

Pitot covers are also not installed while doing maintenence activity during night halts when the aircraft is powered up.
As they could go in heating mode when doing several tests on ground like the LGCIU test which puts the aircraft in air mode or engine runup.

there have been many cases where the maintenence personell have forgotten to remove them while carrying out the tests and have resulted in melting of pitot covers, which means the pitot either have to be changed or thoroughly cleaned.
 
Bravo1Six
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RE: Why No Pitot Covers On Airliners?

Tue Jul 26, 2011 8:13 pm

Quoting RCnoob (Reply 13):
Yes, pitot covers could lead to disaster if not removed.

The flipside of that is that lack of pitot covers could lead to disaster in situations where they should have been put on but weren't (i.e., blockage by insect, dirt, etc.).
 
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HAWK21M
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RE: Why No Pitot Covers On Airliners?

Wed Jul 27, 2011 6:37 pm

Quoting dhawald3 (Reply 14):
there have been many cases where the maintenence personell have forgotten to remove them while carrying out the tests and have resulted in melting of pitot covers, which means the pitot either have to be changed or thoroughly cleaned.

True....Occurs quite frequently,hence the checklist has this in bold to prevent such occurances & it does help.

Quoting RCnoob (Reply 13):

Yes, pitot covers could lead to disaster if not removed. In 1996 an Air Peru 757 had a CFIT disaster due to the static ports being covered.

They used tape which was not visible in low light.Now the AMM clearly illustrates the sequence & type of tape to be used with reflective streamers attached.
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wn700driver
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RE: Why No Pitot Covers On Airliners?

Thu Jul 28, 2011 3:17 am

Quoting HAWK21M (Reply 16):

True....Occurs quite frequently,hence the checklist has this in bold to prevent such occurances & it does help.

On of our E190s took off like this about a year ago; pitot covers melted completely to the surfaces and a series of disagree messages came on as a result. Scary indeed.

Quoting HAWK21M (Reply 16):

They used tape which was not visible in low light.Now the AMM clearly illustrates the sequence & type of tape to be used with reflective streamers attached.

Must be reflective, and like door outlines, it must contrast sharply with the local portion of the livery as well. We now have three different tape colors for this use.
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HAWK21M
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RE: Why No Pitot Covers On Airliners?

Sun Jul 31, 2011 8:08 pm

Quoting wn700driver (Reply 17):

On of our E190s took off like this about a year ago; pitot covers melted completely to the surfaces and a series of disagree messages came on as a result. Scary indeed.

I did notice another Airline A320 pushback prior to start up from a distance & noticed the pitot covers were still installed,So ran over to tell the ground crew who thereafter were in a panic state before calm set in.....I was treated like a hero then..... 
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