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Converting Aircraft  
User currently offlinePilotNTrng From United States of America, joined Dec 2003, 897 posts, RR: 3
Posted (6 years 7 months 1 week 4 days 8 hours ago) and read 2688 times:

Obviously airlines that are buying used aircraft would like them to be similiar to the aircraft that they own.Sch as Delta buying AA's old TWA 757s, because of the type of engines they use. My example and question is, how hard would it be to replace a 757 with a GE engine with a RR and get them compatible with the rest of the fleet?


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23 replies: All unread, jump to last
 
User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 1, posted (6 years 7 months 1 week 3 days 22 hours ago) and read 2579 times:



Quoting PilotNTrng (Thread starter):
My example and question is, how hard would it be to replace a 757 with a GE engine with a RR and get them compatible with the rest of the fleet?

It's technically possible but difficult and expensive. New strut, new aisle stand, some new overhead panels, new wiring from the engine to the aircraft, new reversers. The difficulty of doing the conversion is exactly why the 787 was designed for engine changes from the beginning.

Tom.


User currently offline2H4 From United States of America, joined Oct 2004, 8955 posts, RR: 60
Reply 2, posted (6 years 7 months 1 week 3 days 21 hours ago) and read 2543 times:
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Quoting Tdscanuck (Reply 1):
The difficulty of doing the conversion is exactly why the 787 was designed for engine changes from the beginning.

Interesting that other models (eg: 757/767) weren't designed similarly. It seems obvious that such interchangeability would add value to an aircraft with multiple engine options.

2H4



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User currently offlineFuturecaptain From , joined Dec 1969, posts, RR:
Reply 3, posted (6 years 7 months 1 week 3 days 21 hours ago) and read 2537 times:

It has been said that all things considered it is cheaper to buy a new aircraft from the manufactuer then it is to do this kind of conversion and get the plane recertified for normal pax operations.

But, if you don't want to use the plane in passenger service again...slap a GE-115 on a 747.

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User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 4, posted (6 years 7 months 1 week 3 days 21 hours ago) and read 2529 times:



Quoting 2H4 (Reply 2):
Quoting Tdscanuck (Reply 1):
The difficulty of doing the conversion is exactly why the 787 was designed for engine changes from the beginning.

Interesting that other models (eg: 757/767) weren't designed similarly. It seems obvious that such interchangeability would add value to an aircraft with multiple engine options.

It was mostly driven by the shift from purchase to leasing. When the 757/767 were being designed, legacy carriers owned most of their fleets. Leasing was viewed as something for lower tier airlines. This meant that airplanes were bought straight from the manufacturer to their operator and stayed there for decades...no real demand for the ability to swap engines so little perceived value.

Fast forward 20 years and leasing companies are the biggest fleet owners out there and aircraft can go through 5+ owners in their lifetime. What the buyer (the leasing company) is looking at now is total return on their asset, not just efficiency within a particular fleet/route structure like an airline would look at. The ability to swap engines is of major value to the leasing company (although still of relatively low value to any particular airline) so, like any good supplier, the OEM's are adapting to what their new customers want.

Tom.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6370 posts, RR: 3
Reply 5, posted (6 years 7 months 1 week 3 days 21 hours ago) and read 2525 times:



Quoting Futurecaptain (Reply 3):
But, if you don't want to use the plane in passenger service again...slap a GE-115 on a 747.

I always found it hillarious that GE chose a Pratt-powered bird as their engine test bed  laughing 



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User currently offlineTdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 6, posted (6 years 7 months 1 week 3 days 18 hours ago) and read 2472 times:



Quoting KELPkid (Reply 5):
I always found it hillarious that GE chose a Pratt-powered bird as their engine test bed

Makes sense to me...get your test bird and do a little competitive "research" at the same time. Thanks to the way the FAR's work for maintenance documentation, Pratt would have to turn over all of their maintenance material to GE if GE was flying Pratt engines.

Tom.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25117 posts, RR: 22
Reply 7, posted (6 years 7 months 1 week 3 days 17 hours ago) and read 2447 times:

A small number of 747s were converted from P&W to GE engines. This is one of them:

P&W:


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Photo © Ed Groenendijk
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Photo © Marc Lehmann



GE:


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Photo © Jordi Steeno
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Photo © Tim Perkins



That aircraft was written off after a landing overrun incident at DUS in 2005.


User currently offlineMetroliner From United Kingdom, joined Jan 2007, 1067 posts, RR: 1
Reply 8, posted (6 years 7 months 1 week 3 days 17 hours ago) and read 2434 times:

Here's a dumb question - did any aircraft ever use more than one engine type?

Tridents excepted  Wink I know about those!

Toni

P.S. Any jokes about BAe146s having five hairdryers are anticipated forthwith...



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User currently offlineViscount724 From Switzerland, joined Oct 2006, 25117 posts, RR: 22
Reply 9, posted (6 years 7 months 1 week 3 days 16 hours ago) and read 2420 times:



Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?

Yes, a few aircraft that used a mix of piston and "helper" jet engines to provide additional power during takeoff at at heavy weights. The Boeing B-36 was probably the most notable with 6 piston engines and 4 jet engines.


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Fairchild C-123 Provider military transport.


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Lockheed P2V Neptune maritime patrol aircraft.



Fairchild C-82 Packet (the one in the photo was used by TWA to ferry replacement Constellation engines around Europe). Note the single small jet engine on top of the fuselage.


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User currently offlineStarlionblue From Greenland, joined Feb 2004, 17015 posts, RR: 67
Reply 10, posted (6 years 7 months 1 week 3 days 16 hours ago) and read 2416 times:



Quoting Metroliner (Reply 8):
P.S. Any jokes about BAe146s having five hairdryers are anticipated forthwith...

Actually they're 5 APUs. Big grin



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlineKELPkid From United States of America, joined Nov 2005, 6370 posts, RR: 3
Reply 11, posted (6 years 7 months 1 week 3 days 15 hours ago) and read 2404 times:



Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?

IIRC, UPS'es 727's had Rolls-Royce Tays on the outside positions and they left the JT8D in the center (#2) position...

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User currently offlineTimz From United States of America, joined Sep 1999, 6813 posts, RR: 7
Reply 12, posted (6 years 7 months 1 week 3 days 15 hours ago) and read 2401 times:

IIRC, you don't recall correctly.

User currently offline57AZ From United States of America, joined Nov 2004, 2550 posts, RR: 2
Reply 13, posted (6 years 7 months 1 week 3 days 13 hours ago) and read 2382 times:



Quoting Timz (Reply 12):
IIRC, you don't recall correctly.

Correct. The enlarged air intake on the No. 2's S-duct was a requirement due to the volume of air required for the Tay to operate.



"When a man runs on railroads over half of his lifetime he is fit for nothing else-and at times he don't know that."
User currently offlineViscount724 From Switzerland, joined Oct 2006, 25117 posts, RR: 22
Reply 14, posted (6 years 7 months 1 week 2 days 14 hours ago) and read 2297 times:



Quoting KELPkid (Reply 11):
Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?

IIRC, UPS'es 727's had Rolls-Royce Tays on the outside positions and they left the JT8D in the center (#2) position...

You're thinking of the Super 27 conversion program. A few 727s had the outer engines replaced with the JT8D-217/219 as used on the MD-80 but the original JT8D-15/17 was left in the center position. I think that's because the larger diameter fan on the -217/219 would not fit the center position without major changes. Super 27 photos below.


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Photo © Gert Rosmann



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Photo © T.Laurent
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Photo © Samuel Schneeberger



User currently offlineKELPkid From United States of America, joined Nov 2005, 6370 posts, RR: 3
Reply 15, posted (6 years 7 months 1 week 1 day 21 hours ago) and read 2247 times:



Quoting Viscount724 (Reply 14):
You're thinking of the Super 27 conversion program.

Ah, thanks. I knew I wasn't full of crap then, just couldn't remember which 727 conversion program it was  Smile



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineCaptOveur From , joined Dec 1969, posts, RR:
Reply 16, posted (6 years 7 months 1 week 1 day 7 hours ago) and read 2206 times:



Quoting Metroliner (Reply 8):
Here's a dumb question - did any aircraft ever use more than one engine type?



Quoting Viscount724 (Reply 14):
You're thinking of the Super 27 conversion program.

I think this is also called a Valsan Conversion.

Also, I think the last few 727s off the line. The ones that went straight to FedEx might have been built with this feature already in place.


User currently offlineAeroweanie From United States of America, joined Dec 2004, 1608 posts, RR: 52
Reply 17, posted (6 years 7 months 1 week 1 day ago) and read 2185 times:
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Quoting Viscount724 (Reply 9):
The Boeing B-36 was probably the most notable with 6 piston engines and 4 jet engines.

Convair, not Boeing!

Quoting CaptOveur (Reply 16):
I think this is also called a Valsan Conversion.

Yes. Valsan did the engineering, certified it and then went bust. Goodrich/Rohr picked up the pieces and continued it as the Super 27.

Quoting CaptOveur (Reply 16):
Also, I think the last few 727s off the line. The ones that went straight to FedEx might have been built with this feature already in place.

No, Boeing would have nothing to do with the conversion. They were converted after delivery.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 25117 posts, RR: 22
Reply 18, posted (6 years 7 months 6 days 14 hours ago) and read 2095 times:



Quoting Aeroweanie (Reply 17):
Quoting Viscount724 (Reply 9):
The Boeing B-36 was probably the most notable with 6 piston engines and 4 jet engines.

Convair, not Boeing!

Yes, sorry, you're right!


User currently offlineHAWK21M From India, joined Jan 2001, 31679 posts, RR: 56
Reply 19, posted (6 years 7 months 6 days 12 hours ago) and read 2079 times:



Quoting Futurecaptain (Reply 3):
It has been said that all things considered it is cheaper to buy a new aircraft from the manufactuer then it is to do this kind of conversion and get the plane recertified for normal pax operations.

Costs matter in this field.And if the option to buy a new Aircraft is available,why spend on a mod of such nature.
regds
MEL



Think of the brighter side!
User currently offlineCaptOveur From , joined Dec 1969, posts, RR:
Reply 20, posted (6 years 7 months 5 days 9 hours ago) and read 1991 times:



Quoting HAWK21M (Reply 19):
And if the option to buy a new Aircraft is available,why spend on a mod of such nature.

The used aircraft is availible now. The new one might take months or years to be built.


User currently offlineTod From Denmark, joined Aug 2004, 1724 posts, RR: 3
Reply 21, posted (6 years 7 months 5 days ago) and read 1960 times:



Quoting Aeroweanie (Reply 17):
Valsan did the engineering, certified it and then went bust.

Didn't Valsan hire Flight Structures to do the cert work?

Tod


User currently offlineAirfoilsguy From , joined Dec 1969, posts, RR:
Reply 22, posted (6 years 7 months 4 days 19 hours ago) and read 1930 times:



Quoting Futurecaptain (Reply 3):

But, if you don't want to use the plane in passenger service again...slap a GE-115 on a 747.

Why stop at 1? Put 4 on it. Would probably rip the wings off at full thrust but take off distance would probably be significantly reduced.  Smile


User currently offlineKELPkid From United States of America, joined Nov 2005, 6370 posts, RR: 3
Reply 23, posted (6 years 7 months 4 days 9 hours ago) and read 1888 times:



Quoting Airfoilsguy (Reply 22):
Why stop at 1? Put 4 on it. Would probably rip the wings off at full thrust but take off distance would probably be significantly reduced.

I can just see it now: The Air Planes 747 SST conversion, or the Riley Rocket 747  Silly



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
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