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Chock Spacing Between Wheel  
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Posted (1 year 2 months 4 weeks 18 hours ago) and read 3581 times:

For reasons known to prevent the chocks biting into the wheel due to added weight by loading of pax/cargo and refuelling, the manufacturer has recommended a spacing to be maintained between the wheels and the chocks, irrespective of the parking brake position.

On some Aircraft the AMM states to keep a 6-12 inch gap between the chocks and wheel. Isn't a 2-3 in gap more realistic considering that the Aircraft could move a foot fwd or aft during a cargo loading ops on the main deck [for freighters], this could strike an GSE located around the Aircraft, also refuelling wont cause the wheels to grip the chocks beyond 3 inches.

Any reason as to why 6 inches to 12 inches....Just seems a bit too much gap.


Think of the brighter side!
23 replies: All unread, jump to last
 
User currently offlineDaleaholic From UK - England, joined Oct 2005, 3204 posts, RR: 13
Reply 1, posted (1 year 2 months 3 weeks 6 days 19 hours ago) and read 3406 times:

Leaving a gap sort of defeats the object of a chock being in place, does it not?

I've seen it done and do question it. Especially on passenger aircraft. If the aircraft rolls forward for any reason, the door could be damaged when connected to an airbridge...



Religion is an illusion of childhood... Outgrown under proper education.
User currently offlinemusang From United Kingdom, joined Apr 2001, 845 posts, RR: 7
Reply 2, posted (1 year 2 months 3 weeks 6 days 18 hours ago) and read 3397 times:

Quoting Daleaholic (Reply 1):
Leaving a gap sort of defeats the object of a chock being in place, does it not?

Agreed. It would be interesting to know how much the tyres spread when weight goes from empty to max.

Something I once suggested in the ground handling company I worked for was to put up a sign to show which way the parking stand sloped, and put the downhill chock in contact with the wheel, the upslope chock not in contact.

Too complicated apparently...........

Regards - musang


User currently offlineak907 From United States of America, joined Mar 2012, 40 posts, RR: 0
Reply 3, posted (1 year 2 months 3 weeks 6 days 18 hours ago) and read 3383 times:

I'm familiar only with heavies, 767, 747, 777 - but we rest the plane on the nosewheel chocks only. We put them in place, and the pilot releases the brakes, the plane sits on two chocks. Then we add more chocks on the main wheels, but leave about a four inch gap. These are backup if for some reason the nose gear chocks pop out. Now the only GSE I can think of that would be affected if the plane were to move this distance is the entry door stairs, and even then only if it is parked very close. The lowerdeck and maindeck doors are far enough out of the way to be not affected.

Whit this method, the plane doesn't move at all, but I agree, 6-12 inches is kind of excessive. And even if the plane settles on the chocks, it's not too difficult to get them out.

In my five years I have worked at the airport, I have never seen an airplane move because the chocks gave way.


User currently offlineKC135Hydraulics From United States of America, joined Nov 2012, 270 posts, RR: 0
Reply 4, posted (1 year 2 months 3 weeks 6 days 18 hours ago) and read 3380 times:

When I'm refueling a C-17 our TO says to position the chocks 2 inches from the tires. Any other time the chock is to be placed against the tire. If its hard to pull later on you can pull the rear chock and use it as a sort of battering ram to pop out the stuck chock.

User currently offlinecanoecarrier From United States of America, joined Feb 2004, 2828 posts, RR: 12
Reply 5, posted (1 year 2 months 3 weeks 6 days 9 hours ago) and read 3240 times:

Other than the occasional difficulty to remove the chocks as the wheels expand under load pressure have you noticed tire damage because of this? When I was working GA aircraft we typically used wooden wheel chocks, I never saw any tire damage due to them.

When I worked commercial aircraft we used rubber chocks and as mentioned above if we left a small gap (2'' or so) I rarely had a problem removing a chock. Even then we would move the aircraft slightly forward or backward with the tug to relieve pressure between the tire/chock and it would come right out.



The beatings will continue until morale improves
User currently offlineHarryStanhope From Australia, joined May 2012, 20 posts, RR: 0
Reply 6, posted (1 year 2 months 3 weeks 6 days 4 hours ago) and read 3166 times:

I work ground handling for JQ A320's, whenever I receive the aircraft i place the chocks against the wheels. Some guys kick them in but then they become hard to remove due to the loading.

Where I work, Townsville, Queensland - we use to have a procedure to place the chocks an inch or 2 away from the wheels. This gave just the right amount of space between the two..its was never anywhere near 6-12 inches. This procedure was rethought because when someone was connecting the push tug they did not stop in time and nudged the aircraft backward, I guess if the chocks were further away (6 or even 12 inches) the aircraft may have rolled a little more..then again the hand break should always be on  


User currently onlinewn676 From Djibouti, joined Jun 2005, 994 posts, RR: 5
Reply 7, posted (1 year 2 months 3 weeks 6 days 3 hours ago) and read 3136 times:

Never heard of leaving any space. On our Airbus NBs we chock both nose wheels and one of the left mains, and on 757s we chock one of the nose wheels and one of the left mains. Both are done on arrival before any equipment can approach the aircraft and no space is left in either case. It's easy on the single tires to kick the chocks out (or hit the stuck one with the other chock); on the Airbuses you have to be really good at aiming a chock to throw between the two nose wheels if one is stuck.

Maybe on widebodies it's a different story?



Tiny, unreadable text leaves ample room for interpretation.
User currently offlineairportugal310 From United States of America, joined Apr 2004, 3451 posts, RR: 2
Reply 8, posted (1 year 2 months 3 weeks 5 days 22 hours ago) and read 3075 times:

When I worked on the ramp for YX, we would leave 2-3in of space between the chocks and the main (717). Just the way I had been trained. For loading, was the reason I was given.


hit it and quit it
User currently offlineKC135Hydraulics From United States of America, joined Nov 2012, 270 posts, RR: 0
Reply 9, posted (1 year 2 months 3 weeks 5 days 18 hours ago) and read 3030 times:

As mentioned by others, when I have a stuck chalk on a KC-135/C-17 I use the chalk on the opposite side of the gear as a battering ram to pop the other out. Very occasionally the jet will lurch forward slightly but it's not nearly enough momentum to overcome the flat spot on the tires so it doesn't go far.

User currently offlinemusang From United Kingdom, joined Apr 2001, 845 posts, RR: 7
Reply 10, posted (1 year 2 months 3 weeks 4 days 12 hours ago) and read 2915 times:

Quoting wn676 (Reply 7):
and on 757s we chock one of the nose wheels

Interesting! I worked for a handling company once, and one nosewheel of a 727 was chocked, on a sloping stand. When the hydraulic pressure bled off, the aircraft rolled gently foreward and the nose leg pivoted around the chock i.e. steered the nose gear about 45 degrees before stopping.

Regards - musang


User currently offlineFlyDeltaJets From United States of America, joined Feb 2006, 1787 posts, RR: 2
Reply 11, posted (1 year 2 months 3 weeks 3 days 20 hours ago) and read 2819 times:

UA policy is to have the chock to touch the wheel so that there is no space between the wheel and the chock to prevent jumping of the chock.


The only valid opinions are those based in facts
User currently offlinenwcoflyer From United States of America, joined Jun 2003, 687 posts, RR: 14
Reply 12, posted (1 year 2 months 3 weeks 3 days 20 hours ago) and read 2808 times:

US policy is one tire on each side of the nose gear is chocked with no gap. Additionally, the right main is to be chocked as well- both sides- no gap on turns. On RON's All 3 sides of the a/c must be chocked. Seems that leaving big gaps indeed does defeat the purpose of chocks. Wonder where OAL policies differ. Yes chocks get wedged from time to time. Most of the time just kicking the chock out or hitting it with another chock before departure does the trick. Once in awhile I would have to pull the aircraft forward a little prior to push in order for a chock to be removed.


The New American is arriving.
User currently offlinemusang From United Kingdom, joined Apr 2001, 845 posts, RR: 7
Reply 13, posted (1 year 2 months 3 weeks 3 days 17 hours ago) and read 2776 times:

Quoting nwcoflyer (Reply 12):
US policy is one tire on each side of the nose gear is chocked with no gap.

Good point. Only a small proportion of the weight rests on the nose gear anyway (something like 6% depending on C of G?).

musang


User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 14, posted (1 year 2 months 3 weeks 2 days 21 hours ago) and read 2674 times:

Almost everyone agrees to the no gap or 2 inch max gap......Why does Boeing not revise the AMM that states 6-12inches gap on the B757.


Think of the brighter side!
User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1208 posts, RR: 3
Reply 15, posted (1 year 2 months 3 weeks 2 days 15 hours ago) and read 2646 times:

Our policy is to chock the nose-gear only until chocks are in place on the main(s), then they are removed. Reason: Suspect damage to nose-gear mount may happen during loading and un-loading operations. Please note, this is a freighter operation.

That's the global rule we're operating to, and is valid for every single of the 60+ carriers flying for us .... except for a single American one who "knows better".

We do not leave a gap between the chock and the wheel. Boeing has been rather inconsistent in its recommendations, so we've learned to disregard them and do what we know works.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 16, posted (1 year 2 months 3 weeks 21 hours ago) and read 2474 times:

Quoting B777LRF (Reply 15):
Please note, this is a freighter operation.

what type.....

Quoting B777LRF (Reply 15):
Boeing has been rather inconsistent in its recommendations, so we've learned to disregard them and do what we know works.

whats regulatory's take on that......



Think of the brighter side!
User currently offlinecanoecarrier From United States of America, joined Feb 2004, 2828 posts, RR: 12
Reply 17, posted (1 year 2 months 3 weeks 8 hours ago) and read 2412 times:

Quoting HAWK21M (Reply 14):
Almost everyone agrees to the no gap or 2 inch max gap......Why does Boeing not revise the AMM that states 6-12inches gap on the B757.

I'd say that of all the operations I had to look up in a manual, the aircraft manufacturer's recommendation on chock spacing was something I'd never even thought about doing. It seems like most of us learned how to do this by a coworker when we originally started working in ground ops. Even if Boeing revises the AMM, I doubt it would change operationally how wheel chocks are placed.



The beatings will continue until morale improves
User currently offlinejetmatt777 From United States of America, joined Jun 2005, 2725 posts, RR: 34
Reply 18, posted (1 year 2 months 3 weeks 7 hours ago) and read 2402 times:

I usually leave a 2 cm gap.


No info
User currently offlinefr8mech From United States of America, joined Sep 2005, 5098 posts, RR: 12
Reply 19, posted (1 year 2 months 3 weeks 6 hours ago) and read 2387 times:

Quoting HAWK21M (Reply 16):
whats regulatory's take on that......

The regulatory authority probably doesn't care so long as an approved procedure is written down and adhered to...and the company's procedure is more stringent that the manufacturer's.

So, if Boeing says 6 inches and company procedure says 2, you're good to go...if company procedure says 8 inches, then they need to provide justification for the deviation and chances are, the manufacturer would have to buy off on it.

Quite a waste of resources for chock placement.



When seconds count...the police are minutes away. Never leave your cave without your club.
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 20, posted (1 year 2 months 2 weeks 6 days 16 hours ago) and read 2312 times:

Quoting fr8mech (Reply 19):
The regulatory authority probably doesn't care so long as an approved procedure is written down and adhered to...and the company's procedure is more stringent that the manufacturer's.

It could be the otherway around....The company has a more practical relaxed safe procedure than the manufacturer.....who decides that...Regulatory....right.



Think of the brighter side!
User currently offlineB777LRF From Luxembourg, joined Nov 2008, 1208 posts, RR: 3
Reply 21, posted (1 year 2 months 2 weeks 6 days 9 hours ago) and read 2264 times:

Quoting HAWK21M (Reply 16):
what type.....

All of them (every single Boeing jet, MD-11, DC-8, A300 .....)

Quoting HAWK21M (Reply 16):
whats regulatory's take on that......

None what so ever. Our GOM lists a set of procedures that we, as a corporation, has signed off on. It's only if they're found to be seriously wrong, and results in something dramatic and expensive happening, the regulator will ever get involved in such nitty-gritty details. What's more important is what the industry has to say, in this case IATA via their IOSA and ISAGO certifications, and they're absolutely fine with it.



From receips and radials over straight pipes to big fans - been there, done that, got the hearing defects to prove
User currently offlinefr8mech From United States of America, joined Sep 2005, 5098 posts, RR: 12
Reply 22, posted (1 year 2 months 2 weeks 6 days 6 hours ago) and read 2236 times:

Quoting HAWK21M (Reply 20):
It could be the otherway around....The company has a more practical relaxed safe procedure than the manufacturer.....who decides that...Regulatory....right.

That's why if, in this case, the operator wants to increase the distance, that operator must seek approval from the manufacturer, but decreasing the distance does not require approval.

Also, the various procedures manuals, GOM, GMM, GPP (whatever a particular operator calls them) are approved by the FAA (here in the States)...so, presumably, they've bought off on the 2 inch policy we have.



When seconds count...the police are minutes away. Never leave your cave without your club.
User currently offlineHAWK21M From India, joined Jan 2001, 31573 posts, RR: 57
Reply 23, posted (1 year 2 months 2 weeks 5 days 15 hours ago) and read 2180 times:

Quoting B777LRF (Reply 21):
It's only if they're found to be seriously wrong, and results in something dramatic and expensive happening, the regulator will ever get involved in such nitty-gritty details.

Shouldn't Regulatory be proactive rather than reactive.

Quoting fr8mech (Reply 22):
the operator wants to increase the distance, that operator must seek approval from the manufacturer, but decreasing the distance does not require approval.

Its not necessary that reducing the distance is a better option than increasing the distance......Things could go wrong/or not go wrong on both ways.



Think of the brighter side!
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