Semi automatic procedure is feasible if before shut down dry motoring cannot be performed for any reason and APU is not available.

Before going on, set MFD CPL, MCDU CPL & PIL brakers out, RCP to MFD CPL only, all electrical power consuming items set wisely OFF.

Check BATT not bellow 20V and residual ITT between 250° / 280° C.

ENG#1 only, battery start procedure setup (leave all systems checks for after start).
GOV switch: AUTO
ECL: OFF (using beeper trim)
FUEL boost and switch: ON both
ENG switch: IDLE
---wait 5 to 7 seconds, check ITT must decrease---
NG @15% minimum
ECL: IDLE (min) using beeper trim.

example:
A/C long nose, 44Ah & 27Ah batteries installed, EAPS installed, supp. 85 NOT installed, startup @ SL and OAT 50°C, BATT: 20V and residual ITT:280°C: ITT peak on startup could be around 780°C for less than 1 second.

If MFD goes blank: abort procedure or count seconds and push ECL to IDLE anyway, remember the hot start graphic assessment gives large margin to ITT vs time.

cheers

Hi Crab,

External GPU recharges batteries much slower than onboard Generators. GPU recharges at about 75Amps and it rapidly ramps down. Aircraft Generators push 200+Amps into the batteries after start.

I used to use GPU recharging where we had hangar power for the aircraft, but not a GPU on the line. Top up the batteries before pushing out to the line to make sure every last Volt was in there!

One thing that catches many people out is when they use a battery cart (as opposed to a diesel GPU.

Once the battery cart voltage drops below the aircraft battery voltage (like during a start because the 139 sucks so much out of the batteries), the aircraft battery will try to charge the battery cart as well as try to start the engine. You're better off not using a battery cart at all. Diesel GPU or nothing.

There is no diode or reverse current relay on the External Power circuit.

Skilled crew can move through the checklist pretty quick, with a good copilot and batteries I could get all the RFM battery start system checks done and still have 23v for the start. With suspect batteries nobody I knew would do any systems checks before a battery start. If it was fine when shut down, then likely so on start - helicopter doesn't know if it is the same day or the next. Also depends if dicking around until below 23v results in sleeping in the back of the helicopter for a couple of days instead of back in your 5 star hotel. 139 always had lower than normal battery voltage, heard of some operators adding an extra 1.5v cel to the battery pack. BTW, I knew of some offshore operations where the pilots have never done a battery start, only GPU, and in fact battery starts were prohibited by ops. Those would never know what condition their battery was in.

Malabo,
what you say is correct..... unless you leave the bird parked in an deep African hangar with monkey helicopter engineers unable to count from 1 to 10 on their two hands junking around and playing pretending they're real engineers....or you work in extreme cold weather like Aosta or Sondrio in wintertime at 3000 meters, or you fly chewed asses in short range hems flying 10 minutes long missions, or you forced to shut down the bird for any reason on a drill ship only to discover the ship GPU is U/S in spite of what the HLL was stating before leaving base onshore (damned offshore operations!).

Also, maybe some of us do not have any copilot because we fly single pilot since the very beginning on type and even so the company check list wisely states if is battery or GPU start as a reminder and as the RFM says the same anyways; it goes without saying that we still don't need any checklist for start up as we do it routinely by heart.

Apart of personal recollections, there are quite some situations where we may be forced to start up bellow 23V without APU unless we love to wait for help on a mountain peak or into a remote jungle.

But mostly, this procedure is designed to avoid hot-starts after flying short legs without carrying APU and no time for the generators to recharge hard used batteries, you know that battery Voltage could be OK but battery Capacity could be not.

Cheers

As Malabo said with a good crew flow you can startup pretty quick. We routinely use ships battery only for the start at our base and ive never seen the voltage drop below 23V prior to starting No1.

Twinbird,

There you go - Buitenzorg got it, and it makes absolute sense although it is not well-described in the manuals. Both the generator control units and the EECs are powered from the essential buses before and during the start, although the power to the starter motor itself comes from the main bus.
Be careful - as Geoffers said, starts below 23v could well be trashing the back end of the engine.
As others have said, if you regularly exercise the batteries by using them instead of GPU to start, they will hold 23v OK. If you always do ground power starts, the batteries rapidly deteriorate. Fortunately, you can fix them by using them, and in fact I have seen batteries recover to normal within several days of being used regularly for starts.
There is also a new-ish modification available (supplement 85 - improved engine starting kit) which gives a bigger aux battery, and connects both the main and aux batteries in parallel for start, which gives a bit more oomph for those operators in situations like those described by Maeroda. It also gives longer endurance following a double DC gen fail.

Just do this and all those problems go away....

Concorde Battery Announces AW139 STC With Multiple Validations | Aero-News Network

Belly tank,

I agree with you, but try to think about doing 10 to 20 flights per day of 10 to 15 minutes each from start to stop and being forced to shut down between flights.
Sooner or later you will face the need to start up with APU or with less than 23V battery voltage.

Nooby - thanks for the reply - it would seem then that the worse case would be finding the battery was low on volts for start, using a GPU to get the engines going and then allowing the generators to rapidly charge the batteries. Again, what about the risk of thermal runaway in this case? Any experience of it?

Maeroda,
Yes I concur with your situation that is a lot of starts a day!. We generally only do 2-3 starts a day and flights 1.5 - 2.0 hrs between starts. All the best:ok:

Does the system allow this? On other aircraft by this manufacturer, connecting a GPU isolates the battery, so it cannot charge it.

On AW139's, recharging main & aux batteries could be accomplish as follows:
- plug GPU (either diesel or electric powered by 3phase) to a/c
- BUS TIE switch ON
- braker BUS CONT 1 out

Monitor time, max charge time is 5 minutes.

But is this technique approved by the manufacturer?

Of course is not, as well as it isn't the semi automatic startup procedure I've described above.

You also have to have Ext Pwr, Master, Main Batt and Aux Batt ON.

Sorry Nooby, I forgot to mention the basic electrical power setting...it was going without saying to me.

If it's not an approved procedure, I for one wouldn't ever try it unless it was a life or death situation. Goodness knows what damage could be done to the aircraft systems if there is a regulator problem with the GPU.

It seems as everybody is an expert on OEM non approved procedures.

Shy torque,
in general, you may be right but this carries the assumption that manufacturers are doctors doctors in everything, and that's not the case talking about Agusta.

But honestly, I've been going on with that startup procedure since around 2008 and there's nothing to be worried about in starting the bird in that way, specially if working (I say working, not hauling from A to B where A and B are well served aerodromes).

Regarding battery charging option and Tottigol: again, since first release to service with whose ****ting OEM batteries equipping the short noses birds, that was one of the ways to have some more juice in the battery theirselves when really doing the job the helicopter was supposed to do according to Agusta.
Job that was definitely out of the reach of the 139 without a little help from the operators (because Agusta didn't know any **** about how to operate the helicopter off airports), hence somebody of us had to go on and think it all the way around to skip the option to be forced to stay overnight on a freezing pinnacle at 4000 meters without appropriate gear in the cargo hold.

This wouldn't be happening with an Airbus H145 for sure.

Actually the battery charging method was developed at Agusta and shown to me (and many other early Customers) by the head of Avionics on the production line as they were also having issues with battery capacity.
That was in 2005 and you'll still find people at Agusta using that method occasionally.