Forum: F-16 Armament & Stores

we have experienced two unexplained hung bombs (MK-82 GP) on two separate occasions. in both the cases there was no SMS MFL and in one case no hung symbology as well. The first time the hung bomb was the six in sequence and second time it was fourth in sequence. ARD 863-1 were found 'not fired'. The firing voltages on the TER breeches were OK so was all the AME including TER, WWP, CRIU, adaptor lead and all.
Pl advise me what else to check. I must be missing something

F-16.net Sponsor

Did you check the go/nogo on the firiring pin to see if it was in limits or insure that the cart that was used in the Ter was not previously used in a fix pin breech, both of these could have caused the malfunction as well.

The above suggestion is good, also make sure the umbilical and the J1 connector are not worn and make a tight fit.

ViperDude

I've done both. They checked out fine. Could SMS Mux bus be the problem? Is it possible the the ARD 863-1 cart fails to initiate all togather? I suspect something in the SMS circuit. Pl help me in this

Had a problem like this with a TER as well, to check that, put TER on station, then connected 5060 testers to each of the stations and continuesly ran drop tests to see what would happen, had failures with the stepping switch bypassing station, TER passed bench check but was still bad, had to replace step switch in TER

How about your J&R's?..and I would check to see with a multi metter that your getting 28VDC down to the breeches.

I thought the JRIUs are meant for the WWP breeches. My problem is with the TER breech and carts not firing

What were your results with putting 3 5060 testers on the TER and performing drops, the 500 tester in the shop will not detect this since it only check that the stepper switch moves, it does not check it at the speed that the aircraft release pulses provide.

Definite TER problem, sounds like it's intermittent, I'd look at the TER umbilical and make sure it's not rocking, even if it is locked in place(orange/red stripe showing), the old worn one's can still rock, next check the pin&ground on the TER lead, finally check your step switch inside. The TER is a completly mechanical animal, no mux comm involved.

hello,
i want to ask about the hung bomb mk82 on station 3, pilot tried to fire the bomb many times but no firing and there was no MFL indication,then pilot tried to jettison the bomb but again the jettison failed.
any one can help to find out the probable causes!

Double check the sensing switch on the station in question. Sometimes the spring will not allow the switch to "see" the bomb, but it will pass 5060 and backshop tests with flying colors due to the spring being depressed by the "cow bells" and when a bomb is loaded the switch could be depressed too far or not far enough.

First what mode was the pilot using to drop with? On BLK 15s in some modes you can set the interval where the step and fire sequence minimum time can be exceeded by the SMS and you may see "hung" bombs on some Ters that have marginal switches/relays. When I was your rep over there at Sargodha I gave the weapons shop a drawing to build a ter tester that would check your ters minimum intervals. Did anyone ever build that tester? The standard backshop tester didn't then do a very good job of testing the ter timing tolerances and it's possible to have a TER pass all tests and still intermittently fail in some release situations because of marginal relays and stepper [Link pending approval]
I wrote a flightline procedure for you guys for checking hung bombs that included checking the weapon station right after flight and "poping" the cart in the untouched breech with the bomb removed. Flt Lt Jalal, the first weapons officer with the first 6 A/c you got, from way back then had the procedures I wrote for the first squadron. It included all the suggestions given in this thread plus some other stuff. See if that is still around somewhere. I don't think I kept a copy but I'll look around in my storage just in case.
Another smart thing to do is track your malfunctions by TER, Pylon, Riu, A/C S/N and keep track of which cables are used by assigning local S/Ns to them too. It's a little more work but can really help you track down intermittent problems. Additionally, though not mentioned out loud, some "malfunctions" tend to follow certain pilots around for some reason
Laughing

Jim McLaughlin

Forum: F-16 Armament & Stores

Unexplained Hung bombs on F-16 block 15, on TER 9/A