AirplaneCrazy From United States, joined May 2006, 26 posts, RR: 0 Posted (3 years 6 months 3 days 14 hours ago) and read 1360 times:
Does the fuel consumption (and thereby range) of an aircraft change as the aircraft ages? Cars will get better gas mileage after they are broken in, so I was wondering if a similar effect happens with airplanes. Perhaps the range actually decreases as the aircraft skin gets dirty or dinged?
Liedetectors From United States, joined Jul 2005, 334 posts, RR: 0 Reply 4, posted (3 years 6 months 3 days 11 hours ago) and read 1299 times:
Quoting AirplaneCrazy (Reply 3):
Do you know how signficant the change can be? Are we talking 1-2%, or more?
Depends no how whipped you let your engine become.
A big killer is fan blade deterioration. As the fan tip wear down, they create gaps. These gaps cause a drop in EPR and a result, N2 must increase to maintian EPR. This, of course, would drive up fuel flow as the engine is now running faster and hotter.
Laxintl From United States, joined May 2000, 12047 posts, RR: 22 Reply 5, posted (3 years 6 months 3 days 11 hours ago) and read 1293 times:
Quoting AirplaneCrazy (Reply 3): Do you know how signficant the change can be? Are we talking 1-2%, or more?
Performance deterioration tends to stabilise in mid age aircraft. Its not uncommon for middle age Airbus and Boeing types to be 5% or more percent from aircraft book performance values.
Many airlines have proactive engine and airframe maintenance programs to win back some of the degradation particularly these days with the high cost of fuel.
From the desert to the sea, to all of Southern California
AirplaneCrazy From United States, joined May 2006, 26 posts, RR: 0 Reply 6, posted (3 years 6 months 3 days 11 hours ago) and read 1293 times:
Quoting Liedetectors (Reply 4): A big killer is fan blade deterioration. As the fan tip wear down, they create gaps
I know the latest GE engine blades are made of a carbon-reinforced epoxy with titanium leading edges. Is there any noticeable difference in the blade wear between these blades and more traditional blades?
2H4 From United States, joined Oct 2004, 8075 posts, RR: 64 Reply 7, posted (3 years 6 months 3 days 10 hours ago) and read 1271 times:
AIRLINERS.NET CREW DATABASE EDITOR
I've always wondered how much weight could be removed from a 40-year-old airliners if you could somehow turn it upside-down and shake out the years and years of dirt, pens, grime, trash, and assorted debris that have collected in all the nooks and crannies...
Kdeg00 From United States, joined Dec 2004, 136 posts, RR: 0 Reply 8, posted (3 years 6 months 3 days 10 hours ago) and read 1267 times:
I was thinking along similar lines last week, looking at the various patches on the engine cowling of my 752. My question was how much additional drag an older airframe had because of the repairs to normal bumps and bruises.
Molykote From United States, joined Aug 2005, 1131 posts, RR: 16 Reply 9, posted (3 years 6 months 3 days 7 hours ago) and read 1240 times:
Quoting AirplaneCrazy (Thread starter): Does the fuel consumption (and thereby range) of an aircraft change as the aircraft ages? Cars will get better gas mileage after they are broken in, so I was wondering if a similar effect happens with airplanes. Perhaps the range actually decreases as the aircraft skin gets dirty or dinged?
Yes.
Aircraft performance deteriorates for a number of reasons with age.
- "Dust Bunnies" and other junk accumulated in nooks and crannies of the airframe.
- Repairs will add weight and be somewhat detrimental to aerodynamics if external.
- Engine deterioration
- Slop in the rigging of flight controls, gear doors, etc.
I'm sure others will have more to add. A deterioration of 2-3% is in the ballpark of "normal" after a few to several years.
AvionicMech From United Kingdom, joined Jan 2005, 315 posts, RR: 4 Reply 11, posted (3 years 6 months 3 days 3 hours ago) and read 1180 times:
Every airline should produce either fuel flow factor and drag factor charts or maybe just a fuel flow factor chart for each aircraft to be entered into the FMC. When a navigational database is loaded to the FMC on older systems it will wipe out the FF and drag factors and they will need to be re entered once the update is complete. At my airline we only enter a FF factor and leave the drag factor at 0.0. This FF figure is updated every 3 months I believe, using actual fuel used for a flight and comparing it to the expected fuel burn.
Most of our aircraft have a figure of around 2-3 but some with a couple of old engines may be as high as 5, but that is unusual.
F14D4ever From United States, joined May 2005, 313 posts, RR: 4 Reply 12, posted (3 years 6 months 3 days 3 hours ago) and read 1168 times:
Quoting Liedetectors (Reply 4): A big killer is fan blade deterioration. As the fan tip wear down, they create gaps.
A bigger killer is turbine blade deterioration. After initial rubs, fan blades aren't as prone to continued tip wear as turbine blades, because in addition to mechanical growth/shrinkage, turbine blades suffer airfoil degradation due to thermal stress, which obviously happens continuously through their life cycle.
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