OBOGS check only for Block 52+ and up?

[boggy123]

Hi guys,

Just curious about the Oxygen system check on the F16 and when that check is carried out.

Is it only the Block 52 models and up where you have to carry out the OBOGS test just before taxi?

How and when do you carry out the oxygen test on older models?

[magnum4469]

I can't speak to the Blk 52, never flew it. But for the older models, O2 check was done as part of normal flows, took all of 2 seconds, visually verify how many liters you had, anything over 2 for local mission was good, or over 3 for cap or cross country mission. Then with mask up reach back select test mask, then emergency on flow, back to normal, then 100% back to normal and done...

[boggy123]

Would this be done before the EPU check? During the EPU check don't you put the OXY on 100%?

[Boman]

Your question is not entirely accurate; Block 50 and 52 are the same except for the engine. Similarly with block 40/42. Hence block 52 is not "above" or newer than block 50's.

[magnum4469]

Would this be done before the EPU check? During the EPU check don't you put the OXY on 100%?

No it is a separate check. You check the O2 first, the EPU check comes later. You don't want to have the EPU fire and find out the O2 system is not working... So when it does come time to do the EPU check you know you have an operational O2 system. Doing the EPU check first or at the same time is not the time to find out your O2 is not working properly while the hydrazine. If I remember correctly the EPU remains safety pinned until the last thing before rolling out of the chocks. This was to prevent EPU firing while ground crew under and around jet in case gen dropped offline. Keep in mind this was for "A" model, it may be different with "C" model since it has a stby gen.

[boggy123]

Of course, that makes sense now. THank you for explaining.