View Full Version : 747 'Fifth Engine Mounting'
According to Simon Calder [yes, I know he is a self-publicising ignoramus] in to-day's Independent, a device for detecting volcanic ash is being developed, by, among others, EasyJet. The device can be fitted in a A320 winglet, or attached to the 'fifth engine mounting' on a 747.
Could someone please advise exactly what and where this mounting is.
The full report can be found at:
Grounded no more: the ingenious bit of kit easyJet claims will help beat the ash cloud - News & Advice - Travel - The Independent (http://www.independent.co.uk/travel/news-and-advice/grounded-no-more-the-ingenious-bit-of-kit-easyjet-claims-will-help-beat-the-ash-cloud-6273832.html)
It's inboard of the inner port engine - used to ferry spare engines. There are various pics on the web as the subject does come up from time to time.
Photos: Boeing 747-312 Aircraft Pictures | Airliners.net (http://www.airliners.net/photo/1051704/L/)
PAXboy
8th Dec 2011, 12:35
The process was developed because wide bodied freighters were not around in enough numbers. They add a fairing to the front fan and to rear of the unit, to reduce drag and to prevent the engine windmilling in the breeze. It's probably very cost effective for a carrier to transport one for themselves, than pay freight charges for one on a metal pallett. Or even pay someone else to ferry it on a schedule rotation to get another 747 operational again more quickly.
vctenderness
8th Dec 2011, 17:05
It was a regular occurence on the 707.
Sygyzy
8th Dec 2011, 19:11
IIRC the whole thing was developed by BOAC/Qantas-in the 707 era as VCness has mentioned)-and they probably still get royalties (they certainly used to) for each engine carried whoever is carrying it.
I believe nowadays that you can (just) get a big fan engine into a wide bodied freighter and so the practice isn't as prevalent as it once was.
To adjust the performance of the a/c carrying the fifth pod the word 'FITTED' was inserted into the FMS to adjust the performance details that were required.
S
I believe the DC-10 also had a 4th engine ferry mount on the wing.
PAXboy
8th Dec 2011, 21:19
I guess the positives of carrying the unit safely inside a frighter are offset by having to strap it securely to a special trolley and having to pay to ship the trolley as well. Then your maintenance people have to, either, get the trolley back to base, or swap it with someone else. Now, they will have a clear process for it but, one thinks, that just slinging it onto a friendly wing would be easier.