Spare engine carriage on a twin
 

Hi all,
this question was put to me lately, and I confess to not having a definitive answer. That being, can a twin engined a/c ie 777, obtain a ferry permit for external spare engine carriage simmilar to the -400? I presume the answer is no, due to the additional drag on one side compounding the asymetric thrust post engine failure.

thoughts, answers?

dartman

I don't know the answer, but I'm glad you asked. Seems to me I recently came upon news which indicated that a 777 engine was carried as cargo (to replace one on an ailing airframe) rather than slung as an external store on another aircraft. At the time I read this I wondered the same thing. Just forgot to ask!

Anxiously awaiting an education...

Dave

Not absolutely certain, but I think the engine dismantles the sticky outy bits to make passage through hold doors easier. Due to its large radius, I don't think a spare engine on wing location is desirable for drag reasons or asymmetric drag.

I doubt that the 777 would be able to carry an extra engine. To ferry a engine underneath the port wing of the B747, you need to have an engine ferry pod. This engine ferry pod is an option that Boeing offers on the 747. The 747s that dont have this spare engine ferry pod, obviously cant ferry a engine underneath the wing.

The only other aircraft that I currently can think of that has a ferry pod is the L-1011.

The fan and fan casing are removed, and after that the core is not very large and so can fit in the door & cargo bay no problem. On arrival the fan area is reassembled & the entire engine then fitted.

The 777 can't take an external ferry engine as it has no external hardpoints spare. I was once told by a wise man the the GE90 in it's transport stand can only fit into one of those big Russian cargo thingys but a RR Trent can fit onto the main deck of a 747F.

Try this link for a pic of what looks like a Lufthansa DC-10 with a pod. (You'll need to scroll down a bit)

http://www.aviationpics.de/tech/tech.htm

Pretty sure the VC10 had this option aswell (looks strange on a rear-engined aircraft)

Yes it did. Less broad pod because of the narrower RR Conway engine. Very rarely see these 5th. engine ferry pods now- engines are so reliable these days (doh! Why'd I say dat?)

I find this interesting because the Trent is what Volga-Dnepr is moving with an AN124. In one application for an emergency exemption to the US Sec of Transportation they show the Trent 800 as "26.41 feet long x 12.67 feet wide x 13.167 feet high." In another, "The engine measures 317 inches L x 152 inches W x 157 inches H, with the weight of approximately 25,856 pounds, with support equipment..." (by my math, not EXACTLY the same size, but pretty darned close).

In applying, Volga provides notice to US carriers capable of carrying outsized cargo, and for the most part, there is never a issue. (So long as it IS outsized cargo. They did hit some resistance when they moved a lot of smaller items which really didn't require a single, large airframe...) In other words, if a domestic carrier wanted to chime in and say, "we can do that," Volga might have some trouble getting the contract.

So, I'm not quibbling about the accuracy of LME's observation that the Trent is transportable via 74F. Just wondering, if this IS the case, why is AAL using Volga instead of a domestic 74F? (Yes, I'm clear on the fact that there might not be 74F airframes available when needed, and I'm certainly not trying to stir up any crap regarding the use of foreign/domestic carriers. It's just that I can see a couple of 74Fs from where I sit right now that only get occasional use and I wonder what the deal is).

Dave

'Course, the first swept wing transport jet to do this extra engine bit...was the good 'ole 707, several of the QANTAS aircraft I operated in the past had the hardware installed.

thanks you the info. As a follow up, does the aforementiond hardware on the 747 a customer option, or is it on all 747's.

dartman

Ironic that we Americans hire a foreign aircraft to carry outsize cargo when we invented the wide-body plane perfectly capable of carrying the Trent, GE-90 and the PW whatever...


The mighty C-5 Galaxy


We Yanks are, however, devoted to free enterprise and prefer to let private industry get the work and the money. But the AN-124 is hardly a private operation, is it??

GF

Dartman,

As I wrote in my previous post, it is an option.

Galaxy flyer, in one word HA hahaha...HAha......haaaaaaaaa, get a life
Brgds
Doc

Well... this has taken an ugly turn... :(

AV8boy,
Sorry, didn't mean to insult all americans, its just that I am getting a bit fed up with the whole "we are the greatest" attitude of some of your countrymen.
To get back to the subject, I dont think that carrying an external pod on a 2 engine a/c would be very safe, especially if they where wing mounted engines, think of the extra yaw moment in an engine failure situation.
Brgds
Doc

The 146 carries a spare engine under each wing!

Reminds me of the old joke about the ( very ) senior captain when asked why he was staying on the old 747 classic. His reply: " because they don't make 5 engine airliners";)