Author Topic: How do you zero-time aircraft?  (Read 1829 times)

hmcsnipe

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How do you zero-time aircraft?
« on: May 19, 2010, 01:15:08 PM »
slightly OT, but just a question from a noob aircraft enthusiast:

How would you zero-time an aircraft? let's say it is of the same age as the possibly incoming IAF Cobras.. What's being done to make it possible
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Adroth

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Re: How do you zero-time aircraft?
« Reply #1 on: May 19, 2010, 01:26:20 PM »
For a term as important, and frequently used as "zero-time", I just realized that we've never had a thread that focused just on it. Explanations are scattered all over the place.

Might as well use Mr. H's question as a basis.  :beer:

Here is an interesting definition of zero-timing as explained by the Virginia State Tax Commissioner

See here

The Taxpayer is in the business of overhauling, restoring, rebuilding and repairing airplane parts for various air carriers and commercial operators. The Taxpayer's operation is two-fold. One aspect of the Taxpayer's operation involves a procedure called "zero-timing." Zero-timing is taking a worn aircraft part, i.e. landing gear and propellers, and restoring the part to an "as new" condition as required by Federal Aviation Administration (FAA) specifications.

It is indeed impossible to turn what is old into something that is new. That is impossible. However there is apparently a formal definition for "as new".


Another important term to bear in mind is "Beyond Economical Repair", at which point it would simply be more economical to buy new, than to repair and/or zero-time.

Beyond Economical Repair
« Last Edit: May 19, 2010, 01:28:45 PM by Adroth »
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hmcsnipe

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Re: How do you zero-time aircraft?
« Reply #2 on: May 19, 2010, 01:53:33 PM »
What exactly is being done to make the "zero-timing" possible? What are the processes? How was it being decided whether to buy a new part, or zero-time it? I'm just plain curious.. :beer:

btw, thanks, sir A! :beer:
"...the kingdom of heaven suffereth violence, and the violent take it by FORCE."
"For the word of God is quick, and powerful, and sharper than any two-edged sword, piercing even to the dividing asunder of soul and spirit, and of the joints and marrow, and is a discerner of the thoughts and intents of the heart."  - Hebrews 4:12



"Follow Excellence... Success will chase you, pants down.. o_O"

hughdotoh

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Re: How do you zero-time aircraft?
« Reply #3 on: May 19, 2010, 03:11:02 PM »
Sounds like an interesting business too, that zero-timing. Definitely more exacting a science than plain old restore and refurb.

Ice_Cold

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Re: How do you zero-time aircraft?
« Reply #4 on: May 19, 2010, 03:24:15 PM »
I just did a bit of googling and found a way on how Twin Commander Corporation zero-timed Aero Commander airfcraft with piston and turbines.

Quote
In their case it was a complete strip down and rebuild with new spars, wiring, avionics, the lot. The FAA recognised it by issuing new plates for the airframe with zero hours.

From this forum:
http://www.pprune.org/dg-p-general-aviation-questions/308306-zero-timing-old-airframe.html
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Ignatius1

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Re: How do you zero-time aircraft?
« Reply #5 on: May 19, 2010, 03:57:42 PM »
Here's a blurb about "zero-timing" an F-111:

The task of zero timing an F-111C/G airframe is not as insurmountable as may be commonly believed - the existing 2015 expiry date was largely based on the assumption that no structural spares would be available, either new or used. With the large pool of boneyard airframes now available, used components could be readily sourced. To properly zero time the airframe, the key structural components to be replaced are the wing spars, the fuselage carry through box and upper longerons, as well as some lesser structural parts in the wings. Given the availability of these components, the work could be performed locally. It is worth noting that the cost to manufacture such components in small numbers is today somewhat lower than two decades ago, given the availability of computer controlled 3-axis machines, and integrated computer aided design and production tools.

The issue of extending airframe life in the F-111C/G therefore boils down to the costs involved in either manufacturing and fitting new structural components, or accepting some airframe time on the structure and fitting boneyard wings and components recovered from mothballed USAF airframes. With more than 50 FB-111A/F-111G airframes in the boneyard, availability is not an issue.


The above is from: http://www.ausairpower.net/TE-Subs-vs-F-111s.html

Granted it isn't quiet official, but that's the general idea - replace key structural elements. For aircraft with an abundant support network like the Huey class birds, the idea is pretty common.

Here's a Huey refurb company pamphlet:

http://www.nwhelicopters.com/nwh/pdf/UH-1HReburbishingBrocureforlettersizepaper.pdf

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mamiyapis

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Re: How do you zero-time aircraft?
« Reply #6 on: May 19, 2010, 05:29:14 PM »
The AusAirPower argument that CNC machines can now do the work seems to be warranted... I wonder what kind of machines would be needed to manufacture critical aircraft components from scratch?

Touching briefly on the Israeli AH-1 deal: could we ask for an offset with the deal? Say investment from them in terms of an aeronautics company associated with... helicopter components?

horge

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Re: How do you zero-time aircraft?
« Reply #7 on: May 19, 2010, 08:30:57 PM »
Didn't we discuss this to death in the Jet Pool thread?
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PAFunixGeek

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Re: How do you zero-time aircraft?
« Reply #8 on: May 19, 2010, 08:35:18 PM »
Didn't we discuss this to death in the Jet Pool thread?

Apparently not "to death" :lol:
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Adroth

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Re: How do you zero-time aircraft?
« Reply #9 on: May 20, 2010, 05:07:42 AM »
Didn't we discuss this to death in the Jet Pool thread?

Its actually interesting how this particular topic was discussed as part of other topics, but never as discussed by itself.

Gotta wade through the jet pool thread to quote the good stuff here.
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Ignatius1

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Re: How do you zero-time aircraft?
« Reply #10 on: May 20, 2010, 07:13:24 AM »
Didn't we discuss this to death in the Jet Pool thread?

Its actually interesting how this particular topic was discussed as part of other topics, but never as discussed by itself.

Gotta wade through the jet pool thread to quote the good stuff here.

I believe that the bulk of the discussion on the Jet Pool thread wasn't about the "how" of the zero-time concept. A lot of the discussion pertained to the feasibility of zero-timing certain aircraft due to lack of support mechanisms (parts no longer manufactured, etc.).

Per the Jet Pool thread and some of the information here, "zero-timing" boils down to replacing critical parts of the aircraft structure. According to Aviation Week the Israelis are refurbishing/upgrading their CH-53s to make them last another 15-20 years.
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Adroth

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Re: How do you zero-time aircraft?
« Reply #11 on: May 20, 2010, 07:31:18 AM »
Here my own questions to the pros

Is what was done to the PN Islanders considered zero-timing

Old news but...

Did they overhaul 2 Islanders?

http://www.youtube.com/watch?v=YMX79z051a8

What would be the difference between "zero-timing" and "Inspect, Repair as Necessary" (IRAN)?
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Manokski

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Re: How do you zero-time aircraft?
« Reply #12 on: May 20, 2010, 12:48:41 PM »
Here my own questions to the pros

Is what was done to the PN Islanders considered zero-timing

What would be the difference between "zero-timing" and "Inspect, Repair as Necessary" (IRAN)?

"Inspection and repair as necessary" is exactly what it sounds like.  You check and replace everything that is broken. If a part has time on it that is not broken or needs replacing or is coming due to be replaced, it is not.

Zero timing is more involved including the refurbishment of the fuselage, engines and avionics to a like new condition, often regardless of it's current state.  This is seriously more expensive.  In the end, you get what is basically a new aircraft.

It really all depends on the contract.  What the PAF and the private company agree too. 
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