AS350B3e starts when battery turned on??

[GS Pilot]

Currently troubleshooting an aircraft that is stuck in a pretty remote place.

After landing and shutting down he heard very loud static over the ICS, then the VEMD and Garmin 500 screens went dim.

He turned off the battery and then turned it back on and the start sequence engaged, even though the switch was in the off position. He duplicated it a couple time and recycled the Starter switch a few times...problem persists.

He did let it light off on one of the attempts and had strange VEMD displays and a GOV light came on...not sure if yellow or red.

I do know that this aircraft just a day or two ago had a new Starter Gen put in for troubleshooting, then swapped back to the older one. This aircraft for the last couple years has had very loud static over ICS during the start sequence up until about 12% N1 then it stops. Static only heard on battery starts. If using Start Stick or APU no static is heard.
We have a mechanic headed his way with a new Start Gen but any advice from the collective wisdom here would be greatly appreciated.

Thanks in advance.

[MechEngr]

Sounds like some wires rubbed through or are cut on a metal edge and are shorting power to places power/voltage is not intended to go. The static will be from arcing to whatever damaged the wires. Since it appears related to battery wiring that is a good place to begin the search. Slight other chance - a wire was terminated improperly and a single strand has been deflected to a nearby conductor at a connector. I say slight because that may make electrical noise and gremlin behavior, but will tend to melt before creating a brown-out.

It probably shows up for a limited time when the engine starting torque is highest and that torque is enough to twist the cabling or engine mounting the 0.001 inch required to close the electrical gap.

[wrench1]

He turned off the battery and then turned it back on and the start sequence engaged, even though the switch was in the off position. He duplicated it a couple time and recycled the Starter switch a few times...problem persists.
Trying plugging in a battery cart after landing and before he cycles the BATT switch after shutdown and see if it makes a difference.

This aircraft for the last couple years has had very loud static over ICS during the start sequence up until about 12% N1 then it stops. Static only heard on battery starts. If using Start Stick or APU no static is heard.
Before changing the ST/GEN would recommend opening up the master electrical box in the baggage comp. With this ongoing problem may have a water/corrosion issue with card contacts or relays contacts and its bridging in certain scenarios.

While probably not applicable to this model B3, has the cockpit electrical emergency switch been actuated in recent times?

[JimEli]

stuck K3 starter relay?

[GS Pilot]

stuck K3 starter relay?

Bingo Jim!
More detailed narrative from the PIC below...I was back at base trying to help troubleshoot:


OK it was solved after being stuck in field for 9 hours. Here is what happened and the resolution:After about 2 hours of uneventful flight time (with 9 normal starts/shutdowns), I landed at remote camp about 60 miles from main base. Went to idle, and after 30 seconds, I turned the engine swith off. Approximately 5-10 seconds later, I got loud static in my helmet (radios off already at this point)...after another 10 seconds or so, all screens started flickering and then dimmed slowly as if the battery was dying. The Garmin 500 screens were particularly interesting...they produced colors I've not seen before...very dark purple shades...almost akin to what I've seen some TVs or phone screens do when the screens have been smashed and the backlight fails.
Anyway, at this point, all screens were blank and the panel showed no signs of life, despite the master switch being on. I turned the switch off...waited a few seconds and then back on. A few caution lights illuminated, and one of the Garmin screens flickered bright white briefly...and after about 2 seconds, the caution lights dimmed and died same as before. I turned the master battery switch off....got out my phone to get video of this happening so I could share with Mx. This time when I turne the master battery switch back on, the engine immediate started turning. It repeated this behavior every time the master switch was turned on.
Mx came out and began troubleshooting. In the end, it was the "K3 Starter Contactor" shown below. There are two relays that are easily swappable (K1/2)...but the K3-7 relays are not. Each of those has 4 soldered wires that had to be dealt with.
Yes, we tried banging on the relay, and many other things were checked while waiting for the replacement to arrive.
As soon as the K3 relay was removed and the contacts could be seen...there was obvious signs of arcing and the contactor "bar" (not sure the exact term...but the metal bar that the relay actually moves to make contact in order to close the circuit) was mechanically stuck in the closed position (effectively siezed in the closed position). Mx finished installing a new K3 relay and that solved the problem.
Remaining mystery is the strange behavior of the VEMD and other screens immediately after the initial shutdown. However, once everything was reassembled, the engine started normally and I flew back to base.
Thanks to all for the suggestions. And special thanks to the 2 mechs who came out and dealt with it in single digit temps. For those who asked, the original poster is the base manager here (yes...also a pilot) who was in contact with us in the field via satphone.

[Harrynz]

We had the opposite problem on our B3. The aircraft would occasionally refuse to start when the start switch was selected.

For its entire life, it had this problem and had found itself grounded in various remote locations. Switches, FADECS, and many other boxes had been swapped chasing the source.

Some pilots swore that hitting the rotor brake lever with a hammer fixed it!

It struck me after I ferried it to a local dam to do belly tank bombing with CASA. They wanted their FOI's rated on the tank.

We strapped in for the training and went for a start and got nothing. Very embarrassing. No amount of flicking switches, or tapping/bashing the rotor brake got it going.

They ran out of time and went home and I sat in the paddock waiting for the engineer to arrive.

The engineer was sick of this machine as he had been chasing this problem for years.

I have a background in electronic engineering so I was keen to assist him as he had all the schematics with him. We traced the wires and worked out that there was intermittent ground on the rotor brake microswitch.

It was intermittent in a way that if anyone was in the aircraft, standing on the skids or even leaning on the fuselage we would lose the ground and go open circuit.

It took us forever to locate the ground terminal block under the airframe. We had removed all the cowing trying to locate it as the schematics and maintenance manual were very vague in its location. I eventually found it and located the wire by its label.

I could see straight away that the pin was not fully seated into the block. I gave it a push and felt it snap into place. Most likely it had never been correct since it left the factory. It was near enough that when the airframe flexed just right it would go open or close circuit. It was just pure luck that after you landed it was in position that it would start again.

We checked all the other terminals and found no issues so closed the machine up and it started the first time and never had a a problem again.

The only time the engineer has bought beers for the pilot - it's always the other way round!

Oh and then there was this time on a hospital rooftop when an EC145 after the first engine started, refused to start its second engine......:)

[RVDT]

I think you may have recovered the aircraft OK but when you get time back at base you should dig a bit further.

I would be checking the condition of your earth points in the area of the tailboom. Notorious spot for corrosion and often not obvious.

Sounds like you may have had a weak ground for the relay and it not pulling in hard enough due low voltage - hence the noise in the headset of the contacts doing a bit of casual "welding" with the net result it welded closed?

[Hughes500]

The other interesting thing a B3 will do is on remote start. Got into our B3 battery was showing 23.8 volts. Went to start and it wasnt having it. Plugged in remote pack, started fine to idle. Ground crew pulled out remote pack, engine immediately accelerated to full rpm despite throttle being at idle. Gov warning light on. Opened throttle closed it had no effect whatsoever still at full tilt. Phoned engineering who said shut it down . Restarted with no problem. Engineering had another 3 days later do the same thing. Apparently the Fadec thinks the battery is flat so It will wind up to full rpm to charge up the battery. I m not sure this is correct as to why would anyone design the system to do that on a remote start ??? Answers on a post card.

[Harrynz]

Hughes500 - A low battery voltage or "brown out" (Low voltage dip) as you change over from cart to battery can cause the FADECs to fault and the EBACU will step in and command the NR to flight. As you found out it will ignore the throttle position! This should not happen since the FADECs have their own generators attached to the NG shaft but weird stuff does occur.

Watched a B3 start by itself about 30 seconds after it had been turned off by the pilot. The look of confusion on his face was priceless. He had not placed the START switch into the OFF position properly and it skipped back over the gate into the FLIGHT Position. Once the NG had dropped below 10%, The FADEC saw a valid oil pressure signal so decided it needed to do an inflight restart.

And on bad grounds. I had an AS350BA that developed corrosion on the ground plane on the UHF antenna and it was affecting the bleed valve!. When it was raining and you transmitted on the hospital channel, The bleed valve would close. It made no real difference in flight but was not kind to the turbine when at ground idle. Explaining it to Engineering got me some weird looks.

[RVDT]

The other interesting thing a B3 will do is on remote start. Got into our B3 battery was showing 23.8 volts. Went to start and it wasnt having it. Plugged in remote pack, started fine to idle. Ground crew pulled out remote pack, engine immediately accelerated to full rpm despite throttle being at idle. Gov warning light on. Opened throttle closed it had no effect whatsoever still at full tilt. Phoned engineering who said shut it down . Restarted with no problem. Engineering had another 3 days later do the same thing. Apparently the Fadec thinks the battery is flat so It will wind up to full rpm to charge up the battery. I m not sure this is correct as to why would anyone design the system to do that on a remote start ??? Answers on a post card.

I have heard something similar - apparently if you connect ground power without the battery connected you will get similar results. It will start itself OK and go straight to FLY when you pull the ground power plug.

Probably makes sense when you think about it but can be a trap.

[GS Pilot]

I think you may have recovered the aircraft OK but when you get time back at base you should dig a bit further.

I would be checking the condition of your earth points in the area of the tailboom. Notorious spot for corrosion and often not obvious.

Sounds like you may have had a weak ground for the relay and it not pulling in hard enough due low voltage - hence the noise in the headset of the contacts doing a bit of casual "welding" with the net result it welded closed?

Yes we did recover it. It was the Start Relay.
Thanks to all those that posted advice and suggestions here. Much appreciated.