Author Topic: Test Flight report & expected flying life  (Read 34678 times)

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Offline katie_t

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Re: Test Flight report & expected flying life
« Reply #45 on: August 12, 2010, 03:19:11 PM »
Any update on the IFR, which will allow her to transit at high level and above any nasty turbulence? Is there any chance this might be sorted before Leuchars?
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Offline Old Rigger

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Re: Test Flight report & expected flying life
« Reply #46 on: August 12, 2010, 06:37:53 PM »
Just to give an idea of fatigue indexes, the extract below was extracted from a CAA document for a Hunter Permit to fly application and explains the principles and reference documents that are used:

The procedures and limits of AP101B-1307-1 Section 2 Chapter 3C are applicable and the limit life of the aircraft is 100 FI (wings or fuselage). Until a fatigue meter is installed the fatigue is to be calculated in accordance with the unmetered flying formula as laid down in AP101B-1307-1. Equivalent Swiss modifications effectively embodied AP mods 943 and 1330 so calculations for the front fuselage are no longer required. The Fatigue Index to be used per flying hour taken from AP 101B-1307-1, Sect 2 Chapter 3 is:
Aerobatics 0.077
Cross Country 0.008
Low Level 0.027
Gentle high level 0.015

For any period of flying where the sortie pattern is not known the Fatigue Index per flying hour may be taken as:
Front fuselage 0.016
Centre fuselage 0.020
Wing 0.040
Using these figures the Fatigue Index at 2053 hrs 33 mins is 60.37. The fatigue state of this aircraft is therefore considered satisfactory and is to be monitored using the system laid down in AP101B-1307-1 Section 2 Chapter 3C (AL 182) so that fatigue state is known after each days flight.

So even the worst case for say the wings if XH558 has a further 15 FI before any more work is required and you take a higher factor of 0.05 then to use 15 fi would take 300 flying hours, if my calculator is right.
« Last Edit: January 01, 1970, 01:00:00 AM by Guest »

Offline Gully

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Re: Test Flight report & expected flying life
« Reply #47 on: August 12, 2010, 11:16:03 PM »
From vague recollection of a discussion in the VV last year at RIAT, the Sunday display consumed either a quarter or a third of an FI (apologies - can't remember the exact figure). Number of displays is probably more of a factor than hours at this point in '558's life.

Gully
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Offline Old Rigger

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Re: Test Flight report & expected flying life
« Reply #48 on: August 13, 2010, 07:22:19 AM »
Gully it is what type of flying the aircraft does during those flying hours that gives one of the listed fatigue index figures as this is what you times against flying hours to get your FI figure, so take 0.077 for aerobatic flying and times that by the actual flying hours that gives you the FI. So roughly 0.077 x say 35 total hours flying a year (and bear in mind the only element that can be classed as aerobatic is the 8 minutes during the display, and by aerobatic that usually means high g turns, loops etc), so 0.077 x 35 gives an airframe FI of 2.695 for this year, now given the wing MOD was supposed to give XH558 another 15 FI this would equate to another 5 years life from the end of this year, so the limiting factor would be the engines, MONEY or any other critical/short supply spares running out. With a fatigue meter it makes life a tad easier, I have those type of calculations as well, but they are not much different to those listed for aircraft without one.

If you use the sunday display you mentioned and she flew for 1 hour (which she did not) and you times the whole flight by the highest fatigue index which being 0.077 x 1 = you would still only have consumed 0.077 of a airframe FI.
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Offline StAthan lecky

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Re: Test Flight report & expected flying life
« Reply #49 on: August 13, 2010, 05:21:45 PM »
Looks like I have opened up a can of worms with my request for available flying/display hours ! thank you all for your answers let's see how it pans out over the next couple of display seasons,that's if the cash is available !

 :(  :(  :(  :(  :(
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Offline Old Rigger

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Re: Test Flight report & expected flying life
« Reply #50 on: August 13, 2010, 07:58:45 PM »
« Last Edit: January 01, 1970, 01:00:00 AM by Guest »