rjpieces
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Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 2:08 am

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.
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andz
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 2:14 am

I always wondered if a windmilling fan (towed or stationary) is bad for the engine because no lubrication systems are operational.
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KELPkid
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 2:17 am

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 ).
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Goldenshield
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 2:39 am

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
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Tristarsteve
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 2:48 am

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!
 
AA737-823
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 5:56 am

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.
 
oly720man
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 8:06 pm

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
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helvknight
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RE: Towing Planes To Hardstands Harmful In Any Way?

Wed Mar 14, 2007 8:52 pm

If you don't remember to pull back the bridge and close the door it can be detrimental
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ADent
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RE: Towing Planes To Hardstands Harmful In Any Way?

Thu Mar 15, 2007 3:49 am

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).
 
redngold
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RE: Towing Planes To Hardstands Harmful In Any Way

Thu Mar 15, 2007 6:26 am

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...
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PurdueAv2003
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RE: Towing Planes To Hardstands Harmful In Any Way?

Thu Mar 15, 2007 8:26 am

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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ContnlEliteCMH
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RE: Towing Planes To Hardstands Harmful In Any Way?

Thu Mar 15, 2007 11:08 am

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?
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WrenchBender
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RE: Towing Planes To Hardstands Harmful In Any Way?

Thu Mar 15, 2007 11:52 am

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.

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HAWK21M
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RE: Towing Planes To Hardstands Harmful In Any Way?

Thu Mar 15, 2007 1:00 pm

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.
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ReidYYZ
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RE: Towing Planes To Hardstands Harmful In Any Way?

Fri Mar 16, 2007 4:57 am

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.
 
411A
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RE: Towing Planes To Hardstands Harmful In Any Way?

Fri Mar 16, 2007 9:50 am

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.
 
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HAWK21M
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RE: Towing Planes To Hardstands Harmful In Any Way?

Fri Mar 16, 2007 10:54 am

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
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ex52tech
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RE: Towing Planes To Hardstands Harmful In Any Way?

Fri Mar 23, 2007 3:27 am

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.

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G4LASRamper
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RE: Towing Planes To Hardstands Harmful In Any Way

Fri Mar 23, 2007 8:28 am

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.
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rjpieces
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RE: Towing Planes To Hardstands Harmful In Any Way?

Fri Mar 23, 2007 10:48 am

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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