interpreting component remaining times

[Reely340]

I'm trying to get behind helicopter TBOs and TCIs. I think I understand TBO:
If a used MRGB with a TBO of 1200h and previous usage of 200h
was installed at say 6000h
and I look at the compoment remaining life times sheet at 6600h
the remaining time is 6000 + (1200-200) - 6600 = 400h

Now I'm looking at a "Clutch" with 1200h "service life" (but stating "TCI" not "TBO") that
had a previous usage time of 1300h (well past its TCI),
was installed at 6000h
and the sheet at 6600h says:
"disassemble" at 6100h (! in the past)
"remaining time" -400h (yes, minus)

The ship is claimed to be airworthy and "has fresh 100h checks", mind you.

This either indicates that I don't understand some basic term, or the timekeeping sheet constains invalid data,
especially as I cannot come up with any arithmetic that produces these -400h remaining.

The interesting aspect is, that all other TCI items are calculated exactly liek the TBO items.

Please enlighten me, I'd like to understand these calculations.

[bluesafari]

Reely340
First of all I have not come across the term TCI, please advise on that.
I assume you are installing (for whatever reason) an MRGB with a TBO of 1200 hours of which 200 hour has been used so far in another installation, you then install in an aircraft with 6000 total aircraft hours, am I correct so far? Then the MRGB is due for overhaul at 7000 total aircraft hours. A complication maybe that a component in that MRGB has a different TBO or service life to the MRGB assembly that requires removal from the aircraft to go to a repair facility, that component will be overhauled and the MRGB is then refitted, and the MRGB will still be due at 7,000 aircraft hours. There will probably be components in the MRGB that have service life limits or different TBO. You need to check all component times in connection with MM and the component log cards. You should also be aware that some inspections are part of AD or SB issues, and are not yet part of the MM. All components that have a service life limit will be on the 'life limited' list which should be in the Technical Log.
All components that have an overhaul or inspection interval, will be detailed in the MM chapter 5, chapter 4 will detail airworthiness limitations (service life limits)
Ref your clutch; am not sure what is happening here, when you say TCI do you mean TSI (time since inspection). Remember overhaul and inspection have different definitions. Service life means just that, when a component reaches its ‘service life limit’ it must be replaced, not overhauled or inspected.
Drop me PM if you like, I may be able to help more with a phone call.
bluesafari

[212man]

First of all I have not come across the term TCI, please advise on that

Time Change Item. Basically an item that has to be returned for overhaul (so subject to TBO) or scrap - I think.

[Keepitup]

or Torque Check/Cycle Inspection.
You need to refer to the Ch 4/5 preamble for definition of TCI.


Which aircraft is this on ????


Why complicate replacement times, if its done 200 hrs then it has 1000 hrs remaining (y). Airframe hrs at fit + remaining life of component.


Regarding the clutch, again, need more info. As with the PWC PT6B Engines, they have a thing called FCF (Flight Cycle Factor) which isn't a straight Hr or Cycle, but requires either Automatic calculation or Manual calculations. With the S76B this is done manually. :ok:


But also, as Bluesafari says, be careful of sub-components, as these can have different times as well!!

[Reely340]

Why complicate replacement times, if its done 200 hrs then it has 1000 hrs remaining (y). Airframe hrs at fit + remaining life of component.Exactly my take!

The weird part of the 1200h TCI clutch is that the column denoting "hours done at installation" specifies 1300h,
I'd see that as 100h past end of service life. How can it be legal to install such item in the first place?

Furthermore the coumn titled "remaining time" reads -400h.
How can an a/c be airworthy when even the official log claims that an item is 400h past "TCI life"?

I'm talking about an F28, cared for by an EASA CAMO, mind you.

So I thought the reason must be TBO vs. TCI:
Is it possible that a freewheeling clutch has to be inspected every 1200h
but - as long as it passes the inspection - in fact is on condition?

Maybe sepcifying a TCI of 1200h only establishes a well defined frequency of inspections for OC items? :confused:

edit:
from https://en.wikipedia.org/wiki/Time_between_overhaul
"For aircraft used non-commercially overhauls are not mandatory, but highly recommended."
Is that actually true? A helicopter with lapsed TBO is still airworthy as long as its not used commercially?
(I've learned and witnessed otherwise)

[RVDT]

TCI - Time Change Items

It is an acronym of recent use that is ex-military and or has come from translation to English.

Part of Chapter 4 Airworthiness Limitations -

Chapter 04, “Airworthiness Limitations”, states life limits of time change items, airworthiness limitations

Procedure:
The relevant component must be removed from the helicopter no later than end of life limit. It must either be destroyed or marked in such a conspicuous way as to exclude any, even inadvertent, continuing use.
Life limit must not be exceeded.
When new or used time change items are installed, the nomenclature, part number, serial number and, if applicable, current operating hours must be recorded in the historical record for the helicopter or the component.

i.e. Finite Life which may be flight hours, cycles, calendar time, RINs blah blah and/or a combination.

Chapter 5 -

Sections containing the time limits for the scheduled inspections. The scheduled inspections must be accomplished after the corresponding operating time of the helicopter has been reached at the latest.

This section will contain fluid change periods, lubrication, overhaul periods, and storage lives and conditional inspections such as inspections which must be accomplished either before the next light or in set time intervals after certain operational incidents have occurred, inspections which must be accomplished after accomplishment of certain maintenance measures and inspections which must be accomplished after the aircraft has been operated under special environmental conditions for a longer period of time.

To find the information that you are looking for ask for the component log card.

[Reely340]

update: CAMO boss mailed back, he can't explain that, :O and will dig out the item life documentation.
That item was installed by the previous owner, at a time when they weren't responsibe CAMO for the a/c. :suspect:

[chriswhi]

When I owned my F280 the component card for the clutch was marked retire at 2400 hrs from an inspection at 1200 hrs

[Reely340]

After quite some telephoning I dug out the following:
The clutch is 400 h past life limit, because the TBO was reduced from 2400 to 1200 sometime in between.
(propbably after the crash of a news helo into the Hudson with one fatality, where the clutch was found to have been the culprit).

Hence it outght be replaced, so the heli currently is not airworthy.

Can anyone quote an estimate of the replacement cost?
New clutch is 7500$ ish for the part, how much is the labour?)

[FH1100 Pilot]

After quite some telephoning I dug out the following:
The clutch is 400 h past life limit, because the TBO was reduced from 2400 to 1200 sometime in between. (propbably after the crash of a new helo into the Hudson with one fatality, where the clutch was found to have been the culprit).

I happened to be working for that horrible company back in the mid-1980's. In what turned out to be exceptionally lucky bit of good timing, I quit just before the fatal crash in the Hudson River. The poor schmuck that was flying that Enstrom that day took my place.

Then the federal investigators (not the FAA - they came later) showed up at my door! They had some very specific questions about that operator's maintenance practices. And they had some very interesting information for me.

As I remember, the sprag clutch was manufactured by Dana Industries. Even back then it had a life limit of 1200 hours and was *not* field overhaulable. They were to be returned to Enstrom at the end of their service life.

The DoM at that outfit said that he had taken a clutch from an F-28A apart "just to see how it was built." He put it back together, left it on his workbench and (cough-cough) inadvertently got confused and (cough-cough) "accidentally" installed it on the F-28C that eventually crashed when the clutch let go, killing traffic reporter Jane Dornacker. Nobody believed him. I'll go to my grave hating that DoM. I hope he and the owner of that chicken outfit both get hit by a bus.

[Reely340]

Wow, truly a close call! Thx for that background info about the hudson incident.
I was starting to become a bit worried whether these generous component TBOs and widespread OC items (we remember the once OCed blade spindles, failing at +9000h), while convenient for a caring operator, might be some kind of risk for a buyer, compared to other types.:suspect:

With your info I'd say the messing with the part by the DoM and subsequent installation in the 280C never should have called for halving the TBO, but as nobody believed him they put the blame on the clutch and chopped its TBO.

That clutch sometimes must have had a TBO way past 1200h, as the one in question got installed with already +1300h, so back in 2005 that must have been within TBO.

It's a 28-13401-4, which oddly enough seems to be the one for the 480, according to https://aeroval.com/ref/1528255/28-13401-4 where it says "turbine" :confused:

Should my buddy actually buy that F28, I won't fly it unless he has the clutch swapped. :ok:

[chopjock]

Reely,
(propbably after the crash of a news helo into the Hudson with one fatality, where the clutch was found to have been the culprit).


Why would a failing clutch cause a crash into the river? I would assume a slipping clutch would be a survivable autorotation manoeuvre?

[Reely340]

"WITNESSES OBSERVED THE AIRCRAFT'S MAIN ROTOR BLADES STOP, THE AIRCRAFT DESCENDED RAPIDLY..."
Sounds like some kind of blocked gear(box) due to the clutch falling apart.

https://www.ntsb.gov/_layouts/ntsb.aviation/brief.aspx?ev_id=20001213X35064&key=1

[RVDT]

Enstrom Piston Parts List download (http://www.enstromhelicopter.com/wp-content/uploads/2012/03/Piston-Parts-PricingND-2012.pdf)

2012 Prices Old Data

Over Running Clutch (28-13401-4) USD 7,650.00

Over Running Clutch Overhaul (28-13401-4) USD 5,950.00

Note: Price of a new clutch ($7,750) or a –R clutch ($5,950) will be charged initially. A core credit will be granted only upon successful overhaul of the customer’s used clutch.