JAGflyer
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Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 2:16 am

The gravel kit on the 737-200 is a vital modification for many aircraft that operate in Northern Canada where unpaved strips are common, especially at mining and fly-in only communities. Alaska also has quite a few non-paved airport runways in the more remote areas. As the -200s become old, fuel ineffecient, and costly to maintain why has there been no modification designed to fit more modern aircraft with some sort of unpaved strip provisions? Even some sort of gravel deflector, engine anti-FOD bleed tubes, and a hydraulic area grate/stone guard would be a worthwhile option.

This is obviously a niche market but I'd be willing to bet the cost savings of running a more fuel effecient, winglet-equiped aircraft would quickly recoup the cost of a unpaved strip kit on a modern airliner. Heck, I'd be happy to see a gravel kit install on a 737-300/400/500.
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MrBuzzcut
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 3:15 am

Just my guess, but the clearance height of the engines in a -300 vs that in a -200 is enough to not make a gravel kit as effective. They'd probably be better off using a 717 (out of production, I know) if they wanted newer, and modify that with a gravel kit. Unimproved airfields still exist, but not near to the extent that they did when the -200 was in production, so the likelihood of Boeing or Airbus making those modifications available in new builds is next to nil.

Pretty much the same reasons you don't see built in stairs anymore. So few people need that option that it isn't worth the hassle of designing in the first place.
 
Viscount724
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 3:59 am

Quoting JAGflyer (Thread starter):
eck, I'd be happy to see a gravel kit install on a 737-300/400/500.

I understand the higher-thrust CFM56 engines are too close to the ground to make gravel runway operations feasible. Even if it was possible I doubt there's enough demand from the few existing 732 gravel kit operators to warrant the certification and modification costs.

I believe AS removed the gravel kits from their 732 combis some time before they were retired as they no longer served any airports with unpaved runways.

The current U.S. FAA lifespan limit for the 737-200 is 75,000 cycles or 100,000 hours, whichever comes first, after which they can no longer legally fly and Boeing will no longer support them. Canadian North retired one of their gravel kit-equipped 732 combis (C-GFPW) in July after reaching the 75,000 cycle limit (it had 81,200 hours) almost 37 years after it was delivered to Pacific Western Airlines in December 1976.

Article on page 6 of the following newsletter of the company that's parting it out in YQB, with photo of if it's final arrival there with water cannon salute. Discovery Air, among their various other activities, also owns Yellowknife-based Air Tindi.
http://www.discoveryair.com/app/media/1636
 
drillerscott
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 11:58 am

Cobham here in Perth have had gravel kits certified and fitted to at least two of there RJ100's.
 
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CrimsonNL
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 12:58 pm

Quoting drillerscott (Reply 3):

I used to have a bigger version of this picture but I can't find it anymore. But you should get the idea!



Martijn
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seabosdca
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 2:52 pm

Quoting MrBuzzcut (Reply 1):
They'd probably be better off using a 717 (out of production, I know) if they wanted newer, and modify that with a gravel kit.

This seems to me like a pretty likely next step. Was there ever a gravel kit for the DC-9? If so, that could jump-start the work.
 
yeelep
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Thu Oct 31, 2013 6:22 pm

Quoting Viscount724 (Reply 2):
I believe AS removed the gravel kits from their 732 combis some time before they were retired as they no longer served any airports with unpaved runways.

None were removed, though there were some that never had the gravel kit.
 
Viscount724
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Fri Nov 01, 2013 5:04 am

Quoting seabosdca (Reply 5):
Was there ever a gravel kit for the DC-9?

No.
 
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seabosdca
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Fri Nov 01, 2013 3:45 pm

Quoting Viscount724 (Reply 7):
No.

That's too bad. The 717 otherwise seems like the best aircraft for 732 missions.
 
L-188
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Fri Nov 01, 2013 7:37 pm

Simply stated there isn't near as much all for it with all the airports that have been paved over the past couple of decades.

And if you are only going to do one or two aircraft you aren't going to spend the money to do one or two kits.
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CanadianNorth
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Sat Nov 02, 2013 5:44 pm

Most modern jetliners don't have the required ground clearance for the engines (737 from the -300 up, A320 series), and those that do (717 etc.) don't seem to have any combi mods. One has to keep in mind, at least around Canada/Alaska, the gravel equipped fleet tend to haul just as much cargo as they do people. 60 seats and 3 pallets of cargo on the main deck of a 732 is normal around these parts...

I don't think it would really be worth developing a gravel kit for a modern jetliner unless a combi mod was also done (it's been done for the 734, so it's possible as long as someone's willing to put out some cash). It might be cheaper in the long run to either pave whatever airports are still seeing jet service on gravel strips, and/or perhaps go to a 40-80 seat turboprop catergory airplane and then run a freighter a few days per week (which from what I understand is Alaska's long term idea for now).

Until then I think we'll see what's left of the 737-200Cs being flown till their bitter end, and those ATR72 combis seem like the thing to have for a lot of missions now too. Anyone know if the Q400 is beefy enough to handle freight work? Lots of room up front for a big freight door, and I can't see a combi cert on that being any harder than on the ATR?
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YYZatcboy
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Sun Nov 03, 2013 4:30 pm

Quoting canadiannorth (Reply 10):
Anyone know if the Q400 is beefy enough to handle freight work? Lots of room up front for a big freight door, and I can't see a combi cert on that being any harder than on the ATR?

The Q would have terrible W/B issues if the cargo was in the front. It's a very finniky plane. (Out of the envelope empty, if you want to fly it around empty you almost always need ballast in the back)
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Okie
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Mon Nov 04, 2013 12:41 am

Quoting canadiannorth (Reply 10):
Until then I think we'll see what's left of the 737-200Cs being flown till their bitter end, and those ATR72 combis seem like the thing to have for a lot of missions now too. Anyone know if the Q400 is beefy enough to handle freight work? Lots of room up front for a big freight door, and I can't see a combi cert on that being any harder than on the ATR?

I guess my take on the Q400 and the ATR72 is that from a passenger point of view they seem to be seriously sensitive to weight and balance issues. While a not a small aircraft those two examples are ones that I have been moved forward or towards the back because of balance issues more than other types. I would imagine that it would take some shifting of freight and passengers around at each stop if on a multiple stop route. Somebody is going to have to be good with the old abacus.

Okie
 
unityofsaints
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Tue Nov 05, 2013 12:44 pm

Quoting MrBuzzcut (Reply 1):
Pretty much the same reasons you don't see built in stairs anymore.

The entire Ryanair fleet of 300+ 737-800s has built in stairs.
 
Viscount724
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RE: Unpaved Strip Kits - Why None For Modern Aircraft?

Wed Nov 06, 2013 2:55 am

Quoting unityofsaints (Reply 13):
Quoting MrBuzzcut (Reply 1):
Pretty much the same reasons you don't see built in stairs anymore.

The entire Ryanair fleet of 300+ 737-800s has built in stairs.

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