Radar modification.

If your CH-47 and UH-60 has had either MWO 1-1520-240-50-90 or MWO 1-1520-237-50-84 applied, then you have the AN/APX-118 common transponder, NSN 5895-01-504-0407.

That means the battery replacement requirement has changed. For the new transponder battery, NSN 1635-01-529-0122, there is no specified battery time change requirement.

The status of the new battery is not checked during normal operation and can only be determined through the power up bit (PUBIT) status.

The BATTERY LOW status and FAULT indicator are displayed on the RCU. The LOW BTRY LED will illuminate on the transponder. When the LOW BTRY LED first lights up, replace the battery prior to the next mission.

This info is currently only on Page 5-7 of TM 11-5895-1733-13&P.

The estimated battery life is 6 months (180 days) when the battery is installed in the operating transponder. The battery shelf life is estimated at 24 months (730 days). Rotate your stock by the Date Code stamped on the battery. For example, Date Code 5206 is Week 52, Year 2006. Unit folks, make a note of this until TM 11-1520-237-23 and TM 11-1520-240-23 series manuals are updated.

Make a note that requisitions for the old battery, NSN 1680-01-493-8794, will be cancelled.

Helicopters that had or still have the old transponder computer kit-1C/TSEC (NSN 7021-01253-5641) had a battery that was marked with a 180-day changeout.