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Towing Planes To Hardstands Harmful In Any Way?  
User currently offlineRJpieces From , joined Dec 1969, posts, RR:
Posted (7 years 6 months 1 week 1 day 14 hours ago) and read 3808 times:

I was wondering if towing an aircraft to a hardstand is harmful to the aircraft in any way--not as in passenger safety or anything like that, but rather in effects on the nosegear, longterm wear, costs, etc.

I am asking because I was wondering if airlines prefer terminals/gates where they could have an aircraft with a long turnaround time sit at one gate the whole time as opposed to some terminals, like T4 at JFK, where many planes are towed to hardstands in between flights.

19 replies: All unread, jump to last
 
User currently offlineAndz From South Africa, joined Feb 2004, 8453 posts, RR: 10
Reply 1, posted (7 years 6 months 1 week 1 day 14 hours ago) and read 3800 times:
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I always wondered if a windmilling fan (towed or stationary) is bad for the engine because no lubrication systems are operational.


After Monday and Tuesday even the calendar says WTF...
User currently offlineKELPkid From United States of America, joined Nov 2005, 6381 posts, RR: 3
Reply 2, posted (7 years 6 months 1 week 1 day 14 hours ago) and read 3797 times:

Yes, there are ways to harm an airplane if it is towed improperly.

You can turn the nosegear beyond it's tow limits-definitely a bad thing to do. A jerky tug driver could potentially break a towbar or the towbar connections...towbars even occasionally get broken by very experienced tug drivers  Wink

As far as long-term wear and tear goes, I'd have to say no...any damage from improperly towing a plane will become accutely obvious  Smile The manufacturer designs them for being towed (within reasonable limits  Wink ).



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently onlineGoldenshield From United States of America, joined Jan 2001, 6027 posts, RR: 14
Reply 3, posted (7 years 6 months 1 week 1 day 13 hours ago) and read 3736 times:

Quoting KELPkid (Reply 2):
A jerky tug driver could potentially break a towbar or the towbar connections...towbars even occasionally get broken by very experienced tug drivers

It's those days when you go one way, and the plane goes the other that are bad for anyone.  Wink



Two all beef patties, special sauce, lettuce, cheese, pickles, onions on a sesame seed bun.
User currently offlineTristarSteve From Sweden, joined Nov 2005, 4007 posts, RR: 34
Reply 4, posted (7 years 6 months 1 week 1 day 13 hours ago) and read 3701 times:

Towing does not harm the aircraft at all if done correctly. But ground crews take short cuts and accidents happen. You don't tow an aircraft off the terminal for fun. Either the gate owner needs the gate, or the parking cost at the terminal is much higher than the remote which makes it worthwhile.

When I started at LAP in the 60s (now LHR for you young ones!) BEA operated Viscounts. All the stands were taxi in taxi out. Then T1 was opened and push backs were invented to save space. BEA soon found out that the Viscount nose gear was not stressed for push backs. One good jerk and it broke!


User currently offlineAA737-823 From United States of America, joined Mar 2000, 5813 posts, RR: 11
Reply 5, posted (7 years 6 months 1 week 1 day 10 hours ago) and read 3535 times:

No, it doesn't hurt anything.

the reason to back a plane off of a gate is typically fee$. Gates cost more than ramp space, and premium ramp space costs more than distant ramp space.
I know that Anchorage, just for example, charges a lot more for romeo parking than a certain company leases parking elsewhere on the airport.

As far as windmilling engines, no, not significant harm. There's a lot of oil left in the bearings after shutdown- the scavenge pumps don't take it all out. So I don't suspect there's any harm in it.


User currently offlineOly720man From United Kingdom, joined May 2004, 6724 posts, RR: 11
Reply 6, posted (7 years 6 months 1 week 20 hours ago) and read 3334 times:

I recall reading that there is some impact on the fatigue life of the aircraft when moving on the ground, especially rougher ground.

http://www.trb.org/committees/rps2006/AFD90-RPS06.pdf



wheat and dairy can screw up your brain
User currently offlineHelvknight From , joined Dec 1969, posts, RR:
Reply 7, posted (7 years 6 months 1 week 19 hours ago) and read 3282 times:

If you don't remember to pull back the bridge and close the door it can be detrimental

Swiss A340 PAX Door Broken Off At ZRH (by Swissairtaz Nov 29 2006 in Civil Aviation)


User currently offlineADent From United States of America, joined Dec 2006, 1384 posts, RR: 2
Reply 8, posted (7 years 6 months 1 week 12 hours ago) and read 3085 times:

Branson suggested towing all planes to the runway to save fuel and Boeing said they weren't designed for those loads and in the long run you would wear our/damage the aircraft (IIRC).

User currently offlineRedngold From United States of America, joined Mar 2000, 6907 posts, RR: 44
Reply 9, posted (7 years 6 months 1 week 10 hours ago) and read 2986 times:

I'd say the harm is in not towing the aircraft if it's more likely that taxiing will cause a collision between your aircraft and another... say at LGA...


Up, up and away!
User currently offlinePurdueAv2003 From United States of America, joined Dec 2005, 251 posts, RR: 2
Reply 10, posted (7 years 6 months 1 week 8 hours ago) and read 2937 times:

Aircraft landing gear are designed for slow and short distance towing. Excessive towing, such as towing aircraft to the runway, is something that the manufacturers have probably not done an analysis on or took into account when the gear were designed. Therefore, no manufacturer is going to sanction that procedure until they have data.

The biggest potential harm to an aircraft during towing is ground damage with another object, such as luggage carts, belt loaders, jetways, other aircraft, etc. However, if it weren't for these kind of incidents, I would be out of a job!!!



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User currently offlineContnlEliteCMH From United States of America, joined Mar 2005, 1458 posts, RR: 44
Reply 11, posted (7 years 6 months 1 week 5 hours ago) and read 2903 times:

Quoting AA737-823 (Reply 5):
As far as windmilling engines, no, not significant harm. There's a lot of oil left in the bearings after shutdown- the scavenge pumps don't take it all out. So I don't suspect there's any harm in it.

I either read about this, or I discussed it with an engineer at GEAE while touring the facility. Apparently windmilling can be a source of wear on the fan because the blade roots tend to clack in the hub. I remember as a boy noticing this on the C-5A Galaxy at the Dayton Airshow. The fan blades clacked rather loudly as the engines windmilled -- which is probably why I asked the question years later during the tour.

But... if it causes extra wear, there doesn't seem to be much compelling evidence that it results in any extra maintenance. So who knows?



Christianity. Islam. Hinduism. Anthropogenic Global Warming. All are matters of faith!
User currently offlineWrenchBender From Canada, joined Feb 2004, 1779 posts, RR: 8
Reply 12, posted (7 years 6 months 1 week 4 hours ago) and read 2895 times:

For a period in the mid eighties, we had a problem with our Sea Kings and we were towing them to a contractor for repair. See the link for the route and distance-
http://www.mapquest.com/directions/m...ve&2c=Halifax&2s=ns&2z=&panelbtn=2
Sunday morning at 0130 start time and finished by 0600.
Other than spare wheel assy's and bearings no special precautions needed for the A/C. Police escort and Hydro (power lines) 2 Tugs 1 pulling and 1 spare and off we go.

WrenchBender



Silly Pilot, Tricks are for kids.......
User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 13, posted (7 years 6 months 1 week 3 hours ago) and read 2872 times:

Quoting Andz (Reply 1):
I always wondered if a windmilling fan (towed or stationary) is bad for the engine because no lubrication systems are operational.

Depends on the Speed & duration of the Windmill.Under normal conditions there is enough Oil in the bearings to cater to the rotating disks.

Quoting RJpieces (Thread starter):
was wondering if towing an aircraft to a hardstand is harmful to the aircraft in any way--not as in passenger safety or anything like that, but rather in effects on the nosegear, longterm wear, costs, etc.

It all depends on the person carrying out the towing & the procedures followed.If rules are followed there is absolutely no harm.

Braking,turning angle,speed of towing & clearences maintaining with wing walkers is vry Important.
regds
MEL



Think of the brighter side!
User currently offlineReidYYZ From Kyrgyzstan, joined Sep 2005, 536 posts, RR: 0
Reply 14, posted (7 years 6 months 6 days 11 hours ago) and read 2792 times:

For long term or severe wind conditions, it would be best to throw the engine covers on, not that any one is going to wrestle them on in gale force winds. As far as towing, with the current trend in tractors (towbarless) they are meant to be used as high speed towing units. One person ops, and some companies allow for no brakeriders, but you will still need stairs to go up and set the brakes. I did hear a few years ago that (I could be, and most probably am wrong) UA would do a tow of their 744 to the rwy threshold from an east coast airport, not sure which, to asian destination as the fuel load was that critical.

User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 15, posted (7 years 6 months 6 days 6 hours ago) and read 2733 times:

Aircraft turbofan engines that are left to windmill at the parking stand generally present no difficulty.
The clanking sound you hear is the blades moving slightly against the blade snubbers, as they are designed to do.
Blade snubbers are lubricated from time to time, to be sure that the blades continue to move, for if they did not, fan high vibration would result, which could, in the most extreme cases, cause the engine to be shutdown in flight.
For extended parking, engine covers, if available, should be fitted.


User currently offlineHAWK21M From India, joined Jan 2001, 31684 posts, RR: 56
Reply 16, posted (7 years 6 months 6 days 5 hours ago) and read 2721 times:

Quoting ReidYYZ (Reply 14):
One person ops, and some companies allow for no brakeriders, but you will still need stairs to go up and set the brakes

Out here its Mandatory to have a person on the Brakes and another on the Radio for towing.
regds
MEL



Think of the brighter side!
User currently offlineEx52tech From United States of America, joined Dec 2006, 559 posts, RR: 1
Reply 17, posted (7 years 5 months 4 weeks 1 day 13 hours ago) and read 2515 times:

One of the things that made me cringe was towing a 747 without the body gear steering active. Tight turns are hard on the gear, and the tires.

Towing on ice was always a little nerve wracking, especially an empty A/C.

Ex.



"Saddest thing I ever witnessed....an airplane being scrapped"
User currently offlineG4LASRamper From United States of America, joined Dec 2006, 170 posts, RR: 0
Reply 18, posted (7 years 5 months 4 weeks 1 day 8 hours ago) and read 2491 times:

Regarding windmilling, on the DHC-6-300 at YR we used to tether the props even during relatively short ground turns, due to no lubrication in the reduction gear boxes. Nice to see that fan engines can windmill for the duration of a typical gate stay without this issue.

For towing at G4, we require one person on board to ride brakes and radio.



"A pig that doesn't fly is just a pig." - Porco Rosso
User currently offlineRJpieces From , joined Dec 1969, posts, RR:
Reply 19, posted (7 years 5 months 4 weeks 1 day 5 hours ago) and read 2467 times:

Quoting ReidYYZ (Reply 14):
I did hear a few years ago that (I could be, and most probably am wrong) UA would do a tow of their 744 to the rwy threshold from an east coast airport, not sure which, to asian destination as the fuel load was that critical.

I believe this was true...It was a United 747-400 from ORD-HKG IIRC...


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