TB-43-0001-62-03-1-EXTRACT

TB-43-0001-62-03-1-EXTRACT - Page 2 of 5

TB 43-0001-62-03-1

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Ground Precautionary Messages (GPM) (cont)

(2) Total loss of air from the secondary air tank (only) will result in improper function of the forward relay valve. This,

in turn, limits driver braking to the right side rear axles. Left side of the intermediate axle and rear axle brakes will

not function. Front brakes will not function. Result would be uneven braking with a momentary loss of vehicle

control possible. Probability of such an occurrence happening, however, is improbable or unlikely to occur.

(3) With or without the plumbing error, a total catastrophic loss of both primary and secondary air pressure causes the

vehicle's spring brakes to engage. This, in turn, automatically stops the vehicle as pressures in both tanks plummet

below 60 psi.

USER ACTIONS:

NOTE

The following instructions apply to all units worldwide with M939 series trucks that have been modified by MWO 9-

2320-272-35-1. This MWO was initially issued as MWO 9-2320-272-50-1, "M939 Brake Stabilization Program (Retrofit

of Anti-lock Brake System (ABS) for M939 FOV)".

Inspection. Within 60 days of receipt of this GPM, unit maintenance personnel are directed to inspect ABS equipped

M939 series trucks at the location of the primary and secondary air tanks (below cab, vehicle right side) for correct plumbing.

If found to be incorrect, units are directed to schedule repairs at time of the next semi-annual Preventive Maintenance Checks

and Services (PMCS) for the truck(s) affected. Units may opt to accomplish the repair during any other routine service, at the

discretion of the unit. For USAREUR-based units, repair kits will be distributed directly and automatically through AMC-

Europe. Automatic distribution in Europe is based upon RAILS data of vehicles possibly affected by the mis-plumbing. All

other units worldwide that find this difficulty may order one kit per identified truck through TACOM's M939 Team MWO

Coordinator, AMSTA-LC-CHM, ATTN: James Curtis, curtisj@tacom.army.mil, DSN 786-6484 or Commercial (586) 574-6484.

Such units are also asked to identify the total number of M939 series trucks affected/kits required within 60 days of receipt of

this GPM and to schedule needed repairs for the next semi-annual PMCS. See paragraph E, below, for post-fix "reporting"

instructions. See below for "Supply Status" and additional kit ordering instructions.

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