PS Magazine - TB 43-PS-683
PS, The Preventative Maintenance Monthly
ISSUE 683
OCTOBER 2009
45
PS 683
OCT 09
A
re you running a 100-kW TQG as part of an MEP-807A or PU-807A with an
engine serial number of, or between, BDZ00012 and BDZ01868?
If you are, you can expect the fan drive bearing in the engine pulley group to fail.
The bearing is Item 13
of Figure 19 in TM 9-6115-
729-24P. When the bearing
fails, replace it with a new
bearing, PN 307-9798, NSN
3130-01-572-3243. Add this
part number and NSN to
your TM. The NSN is not
yet on the AMDF so order
it using a DD Form 1348-6
and write in the REMARKS
block that the NSN is not on
the AMDF.
If the bearing has not yet failed, change it at 2,500 engine hours. If the engine has
already run more hours than that, replace the bearing now.
There is no warranty for this part so replacement costs belong to the unit.
If you have any questions, contact CECOM LCMC at DSN 992
-7169 or:
7
edgar.wright
@us.army.mil
13
PAOZZ
PAOZZ
PAOZZ
11083
BEARING
1
Item
No.
Army
Air
Force
USMC
NSN
CAGEC
Part
number
Description
and Usable
On Code
(UOC)
Qty
SMR Code
307-9798
A hot start is when the LRAS3 FLIR has not cooled down. This knocking may be loud
enough for the LRAS3 to be heard beyond 50 meters. The knocking is telling you that the
standard advanced dewar assembly (SADA) cooler is taking a beating and will have a very
reduced life.
If you haven’t heard the knocking, yet, but your Block 1 LRAS3 has a serial number of
1000 or higher, chances are good you will hear it soon. If the serial number is 0999 or less,
you have a Block 0 con±guration and you’re in the clear.
What should you do if you have this knocking problem? You should turn the switch from
STBY to ON. For any other questions about your LRAS3, call DSN
654-4772 or (703) 704-
4772. Or email:
robert.youngblood
@us.army.mil
This does not happen on every LRAS3, and only occurs when not cooled and the switch
is in STBY.
AN/TAS-8A(V)1 & (V)2 LRAS3…
100-kW TQG…
Fan Drive Bearing Failure
lras3 operators and maintainers, have
you heard a loud knocking sound when your
block 1 lras3 is placed in the cooler-only
or standby mode after a hot start?
{ahem}…
you seem
to have
loud
internal
noises.
What’s That Loud Knocking?
Is switch in STBY after a hot start?
Bearing is Item 13 of Fig 19
Add NSN and PN to your TM!
I hope…
I hope… I
hope my fan
drive bearing
doesn’t fail!
683.44-45.indd
1-2
8/22/09
3:46:07 PM
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