Gulfstream info

[Jetdriver69]

For all you Gulfstream guys who may believe the APU is guarenteed to start at FL390, well don't bet the farm on it. A few days ago at about 40W we lost #2 gen. No big deal, #1 gen was working fine, the HMG checked out ok, Kef and Shannon had good weather and, well you always have the APU to start if you need another source of electrics. I don't know about the other G models, but in the GV you will shed the galley master if you lose a gen. Mostly to lose the high draw of the oven, but you also lose underdeck heaters and some lighting. Again no big deal unless you are looking at a long time to cold soak and freeze water lines and if you want to use the toilets. So long story short, we decided to start the APU at our current altitude of FL410 just see if it would start without descending. No luck at 410 and no luck at 390 or 350. We had to get down to 290 before it would start and by then we were just about to Ireland. This minor fiasco could have been a major factor if multiple emergencies, fuel range or weather considerations would have been present. I know most pilots never have a need to start their APU at their operational limits, but this situation makes me think of what else would not work as advertised in an emergency. Just something to think about.

 

[LJ45]

It might be a good idea to do a high alt ops check every once in a while on the APU start. What is the AFM limit on starting the APU for the GV?

 

[Partyfoul]

That sucks JD. I'm wondering if your BAAV is not working correctly. I've started our APU twice at FL390 and it worked fine. I will admit we waited about 2 minutes after the pressing the start button for it to light off. This was before the days we couldn't start the APU in flight of course. Good to hear all turned out ok!

 

[gear_guy]

Not sure about the V but I think the max speed for the APU start in a IV is 250kts or .75

 

[fokkerjet]

Old news. I had the same problem coasting in from Hawaii, lost the GCU, couldn't start the APU at FL390. At the time, we were operating several GV's, and none of them would start after cold soaking. Our tech rep told us, that it's not uncommon for the APU.

BTW, don't be surprised if you have starting problems on the ground too, if your surface OAT is very cold. Had a flight into northern Canada, APU wouldn't start there either...OAT was -20c.

 

[gutshotdraw]

I assume you have an ASC for the APU enclosure sealant since we've been prohibited from operating the APU in-flight for more than a year...


Of course, losing a GEN in flight is an emergency, right????

 

[fokkerjet]

I assume you have an ASC for the APU enclosure sealant since we've been prohibited from operating the APU in-flight for more than a year...


Of course, losing a GEN in flight is an emergency, right????

Mine happened prior to 2002. Single generator load was less than 50%, so didn't worry about it on that leg. Second leg, defered it, and operated with the APU, home. (APU started on ground, with no problems)

 

[Jetdriver69]

Yes we have the ASC and it wasn't an emergency in my opinion. But the fact that it is taught that FL390 is a guarenteed start envelope is about as comforting as "the check is in the mail and I will love you long time". My situation could have been critical if other factors would have been present. I had our V sitting on the ramp in Warsaw for three days straight below -10 and the APU started no problem. I am going to test it out again without a cold soak the next time I fly her at FL390 to see if we have a real problem. Thanks for all the inputs.

 

[gvtech]

Jetdriver,

When did you get the ASC? I was just in SAV last week and was told they were starting the first install as part of the proving process of getting the ASC approval. Was I given incorrect information? Just curious as I tried to get them to use our aircraft for the proving process but our timeframe didn't work.

gvtech

 

[AA717driver]

Long ago, we were required to start the APU at top of descent for ETOPS requirements. The worked pretty consistently so the FAA said we could stop.

What we found out was if you turn on the master and allow the door to fully open, it will spin the turbine and circulate the oil, making it easier to start.

Might be a good practice (once you have the STC).

TC