Ref. TLI (Total Life Index)
Ref. TLI (Total Life Index)
(OP)
Hi, I´m not familiar with the Total Life Index (TLI) concept. I know that if TLI reaches 2.0, the aircraft is permanently grounded; to adopt 1.75 as TLI limit is based upon acceptance of risk and probably of failure. I wonder if someone could tell me how to calculate the TLI for one aircraft ?
julio
julio





RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
But in this case, would you know if is it possible to calculate the limit life of one aircraft with miner´s rule?
If I have an airplane that has 25.000 hs flight limit and I see that it is flying harder, is it possible for me to estimate in advance a new limit life?
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
Is n*s^5 =constant a reasonable first sight approximation for an aircraft?
Cheers
Greg Locock
SIG:Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips.
RE: Ref. TLI (Total Life Index)
and what du you think would be the best structural inspection to attain this reduce service life goals for the a/c? I put outer wing surface upper planks and center wing surface upper planks. Horizontal stabilizer. other ?
thanks
RE: Ref. TLI (Total Life Index)
is the fusealge pressurised ?
is the wing struted ?
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
i'm trying to think of a pressurised, 4-engine plane with a strut wing ... nope, not getting any ...
RE: Ref. TLI (Total Life Index)
But not, forgive me, it is not an airplanes with external braces. I speak about a P3 a/c, which by his nature is very demanded in his maneuver of flight. So, I try to be attentive to the first indications of appearance of fissures. Because of it I wanted to see what might be that of initial damage and incorporate him into this zone an inspection.
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
how does your mission compare with the assumed flight profile ?
talk to Lockheed; the operator should have a support agreement with them.
or are you trying to add something onto the airplane ??
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
this is something that is Way to big to solve in a forum discussion.
if the palne has consistently been flying at a lower AUWt than Lockheed's assumed mission, then there is something to be gained for Most of the structure. the landing gear probably won't change. the fuselage probably won't gain much either, dominated by pressurisation.
Some military planes fly with known cracks, but only after Alot of analysis. They need to prove that the crack will still hold ultimate strength untill the next inspection.
Get some formal training in ASIP, DTA, fatigue, etc. Get some experienced engineers to work through the problem with you. talk to Lockheed. this is a big project, several manyears of effort.
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
word of caution ... if the "missing" weight is fuselage stores, then this is all good; the plane's structure is less stressed. if the "missing" weight is wing fuel then there's a "plus-minus" game being played ... most of the plane isn't less stressed, because wing fuel's weight is reacted by wing lift it comes along for free (as far as the structure is concerned), and if the fuselage is fully loaded then clearly there's no change here.
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
if the plane cruises at about 10,000' pressure stresses would be quite small (insignificant??) but there'd be a whole bunch of other issues (fuel burn, area surveyed, ...). this really doesn't matter, 'cause you're working on a plane that has been operating for several years (no?) and is approaching it's fatigue life, and you're looking for ways to extend it (no?).
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)
RE: Ref. TLI (Total Life Index)