Hard to start R44

[givdrvr]

a friend reports the following...
The 2013 Raven I that I purchased about 2 months ago acts as if the battery is down when I engage the starter. I basically have to keep holding the key and, after about 3 seconds, the engine will turn over slowly, but almost always start when cold. When the engine is hot, the engine will sometimes not turn over fast enough to start. The main rotor blades do not turn when I engage the starter. The main rotor blades start turning about 5 seconds after engaging the clutch. I replaced the battery, which is located under the copilot seat, with a new Concorde RG-25XC and there was no change. A mechanic adjusted the timing of the magnetos, but no improvement. The person I bought the helicopter from said his other 2013 model is slow to turn over also, but his 2015 model does not have this problem. Is the starter different on 2013 and 2015 models?
Any suggestions? Thank you

[misterbonkers]

Is the starter motor ok?

Have you tried starting her with every non required CB pulled?

Are the belts too tight?

Are you priming her correctly?

If you use external
Power does she start a lot better?

[as350nut]

I find that if you can just move the belts about a half inch by hand before they grab on the sheave, you have them loose enough. If you don't get blades turning for 5 seconds after it fires then I don't think it is a belt adjustment issue. New battery, so as long as the battery leads and connections are good (check) then not that. I would bet on magneto, or the " shower of sparks" unit.

[HeliComparator]

There's a lot of talk about magnetos on this thread, but the OP says the problem is not that it doesn't start, but rather that it doesn't turn over, or at least is very reluctant to do so, therefore I can't see what relevance the magnetos have.

If the battery is in good condition and fully charged, (I know it's new, but that doesn't necessarily mean it is in good condition or fully charged!) then I would check the thick wiring between the battery and the starter, including the -ve/ground connection. However most probably it is an issue with the starter motor, such as worn or poorly contacting brushes.

[RINKER]

I am very familiar with internal combustion engines with this kind of problem in general but have no experience on Lycoming. As others have said a lazy starter can cause this but odd it's ok when cold but not hot. Does anyone know if the Lycoming has any valve operated decompression mechanism to lower compression for starting as seen on other piston engines. If so that could be the problem. All it takes with this system is wrong valve clearances and you get this result.

[Ennio]

If safe to do so, use a jump lead direct from battery earth to the starter motor body or mounting bolt. This would be a good check of the fitted earth wire.

[500e]

If wiring good a battery charged suspect starter even if it is new have had more than 1 that was faulty out of box

[claudia]

Yep, lazy starter motor.

[HeliComparator]

... but odd it's ok when cold but not hot. Does anyone know if the Lycoming has any valve operated decompression mechanism to lower compression for starting as seen on other piston engines. If so that could be the problem. All it takes with this system is wrong valve clearances and you get this result.

It's not uncommon to find this sort of problem worse with a hot engine, because the low rpm compression is higher with fresh oil on the bores, slightly less piston to cylinder clearance etc.

No there is no automatic decompression-type system on these engines. Reliability is key and adding a device to deliberately make the engine fail at a certain time (ie by lifting a valve etc) would only reduce reliability.

[Pappa Smurf]

Maybe try a heavier duty battery lead.

[cockney steve]

Sounds like a high-resistance joint.(when it's all warm and expanded, the problem goes away!)..worth cleaning all "earth" connections...including the tags on leads, any washers, metal of engine-casting etc. a smear of Vaseline (petroleum jelly) should be applied to all bright, clean, mating surfaces before reassembly (don't forget the bolt-threads and underside of the heads.
"Pos" connections should also be cleaned (a brass or Stainless-bristle brush is useful) but a smear of ordinary lithium or calcium-oxide base grease is preferable....Vaseline is conductive and a too-generous smear could provide a leakage-path to discharge the battery, pos to earth.
a lazy starter can be caused by sticking brushes, brush"tail" caught on the brush-carrier, weak , mis-placed or broken brush pressure-spring....or,not unknown, Field coils partially-shorted/earthed...Armature solder thrown from Com connections (rarer since they are usually welded/crimped nowadays)
or armature-bearings worn so it binds on the pole-shoes.

A follow-up on the cause and resolution. of your problem would help everyone's understanding....please?

[Eddie Dean]

Is interesting that givdrver has to hold the key at start for a few seconds before the engine cranks over. Perhaps this is an indication worth investigating before changing battery starter magneto or ignition unit

[Efirmovich]

I think Cockney Steve is probably bang on the money. Sounds like a bad connection.


E.

[gustl]

Is this a 14 V or a 28 V (uncommon option) ship?

[cockney steve]

Is interesting that givdrver has to hold the key at start for a few seconds before the engine cranks over.

Which is another indicator of a high-resistance joint!...connection made, current flows through poor connection , which heats up, arcs over and"welds" a connection, or simply expands with heat, tightening the contact and increasing the area sufficiently to carry the required current.

A tight joint is not necessarily sound electrically.......way back in the 60's an engineering lecturer from the Generating Board, said they'd tried multistrand aluminium cables without success. no matter how they tried to clamp the ends, a lot of the strands made poor contact.

Aluminium oxidises instantly on contact with air- even that freshly-polished vintage plane has a film of oxide!

[RINKER]

Cockney Steve I couldn't agree more.
Thread drift alert.
Last year I had the task of sorting 11 ECU / electrical faults on a well known
Solihull 4x4.
One of the main issues turned out to be a known branded ECU which
Had aluminium pins. The corrosion on these was unbelievable.

R

[Helilog56]

Cockney Steve.....go to the head of the class sir....:D