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Old 30th Mar 2017, 15:56
  #17 (permalink)  
RAT 5
 
Join Date: Jun 2000
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I'm going to admit I've re-set systems via an pull/push CB manoeuvre. Indeed, when transitioning to B767 we were taught to re-set a failed FMC via the CB. It certainly wasn't a QRH item, it was an engineering one.
Since then, on various Boeings, I've reactivated VHF, VOR, FMC, Transponder. Two in the air and others on the ground. The 2 airborne avoided a diversion to a maintenance base as the MEL would have grounded the a/c.
However, the sting in the tail. B767 out of LGW, many moons ago, on its way to Canaries; A/T would not engage on takeoff. They continued, as you do, and then, during the mid-level climb, Himself decided on a CB pull/push. I do not know if the A/T recovered, but the RAT deployed. The electrons and circuits had detected, in their mind, a double engine failure when the CB was pulled. OMG Lordy Lordy. They returned LGW for a red-faced landing. Engineers asked why not continue to destination and reset RAT on the ground; RAT has no speed or ALT restriction. Oops! The crew were now out of hours so the debacle grew & grew.
There are some CB's that you might be sure affect only a single non-critical system, and others to be left well alone. I suspect on many of today's Star Wars jets the electrical spaghetti behind many switches has tentacles far beyond our imagination.
An old rule of thumb from carpentry days; measure twice cut once. Re-paraphase for resetting CB's. And be aware of the difference between resetting a popped CB and resetting a system via pull/push.
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