Piper Seneca I right hand engine harder to start?

[tommywcom]

Just wondering if there are design / inherent issues to why the right hand engine might be harder to start than the other one.

When I was doing my multi training on a couple of flight school Semeca I's, my instructor had said something about the RH engine magneto is somehow a little different and less efficient than the LH engine - but at the time I wasn't paying much attention. And even back then, the RH engine was always harder to start. And one time when it was cold (~5 C in Vancouver), we / he couldn't start the RH engine after a few tries, and he got out and got the school maintenance people to preheat the RH engine. It seemed to have done the trick.

Fast forward to now when I have my own Seneca I. I've struggled with hotstarting the RH engine. And now I'm struggling with coldstarting the RH engine too when the weather is colder (5 C). LH engine is never a problem - starts on the first or at the most second crank. So I don't think it's a technique issue and I follow the checklist anyway. On the RH engine, I would typically cycle through the coldstart / hotstart / flooded start procedures just to mix it up. And on the RH engine I have managed to run the battery flat on a few occasions.

Granted there may be differences in engine condition, but I'd prefer to leave that out of the discussion for now and assume the engine condition (eg. TSOH) are the same.

Any ideas?

[DanWEC]

I could stand to be corrected, but ...
The only difference in engine starting in past aircraft is likely just coincidence. If an engine is hard to start there may be an issue with it.
The Seneca that I fly has a left engine that runs a bit colder than the right. Marginally harder to start, and must be kept at a higher warm up rpm.

What kind of primer kit do you have?

Cheers,
Dan

[tommywcom]

Unfortunately I don't have any idea what kind of primer kit is on there ...

[cgzro]

This is just a guess as I have no experience with the left hand rotating engine however Id be suspicious of the impulse coupling. the impulse coupling makes the engine easier to start at low rpm and just like the mags has to be a left hand rotation part.

Also, there were some SBs on some of the Lycoming 360s to set the timing to 20 btdc instead of 25 btdc, if applicable to your engine that would make it a bit easier to start.

These are just guesses however based on operation of a single 360-a1e.

Oh not sure what starter you have but the new light weight ones will spin the engine quite a bit faster and make for easier starts. The difference for example between the prestolites and the stec is dramatic.

[DonutHole]

it will also depend on the mags, some have impulse couplings and some have starting vibrators/shower of sparks, either way, they should start up the same.

[digits_]

Might just be your left hand starter that is more powerfull / newer than the right one.

[GyvAir]

Coriolis effect.
Australian aviation forums are full of threads discussing why the LH engines on their Pipers are so bloody hard to start!

[GyvAir]

And for a potentially helpful answer..

All things being equal, I’ve noticed that just about everybody has a slightly harder time starting the RH engine on most piston twins, for the simple reason that the visual and audible cues as to what’s happening are harder to pick up. Especially true when one is new to the airplane. The manifold drains and the ground under them aren’t easily visible to give you an idea how much you’ve primed, so people tend to over-prime, or they under-prime because they don’t want to accidentally over-prime. Hearing when the engine is just catching, but not quite starting on the retard points, so you can get off the starter button and let the advance points take over with a shower of sparks system is more difficult as well. A flooded engine and an engine that’s too lean to start also sound different while cranking.

[ruddersup?]

GyvAir has the answer I think. I've had this problem with the larger lycomings occasionally on engines that are not counter rotating.
The manifold drain on the right does not drain properly. It tends to flood the engine easily because the fuel pools in the manifold. Going to a flooded start with manifold full of fuel doesn't work either. Mixture will remain way to rich so you are chasing your tail to continue. Try not to over prime it. Try a flooded start right away with starter still engaged if normal start is not successful. On flooded start when it fires do not touch mixture, bring back throttle first and leave mixture lean until it begins to starve for fuel then advance mixture slowly. Good luck.

[iflyforpie]

I'd agree with Gyvair too.... particularly after experience with the Skymaster. If I follow the POH and start the front one first.... it's just about impossible to start the back one because I can't hear or see it. Start the back one first, it works like a charm.

Maybe try starting the right one first since you will have better visual cues to make up for the lack of sound when starting the left.

[Strega]

Do you have Shower of sparks or impulse mags?

If you have shower of sparks, does it seem to always start when you "release" the starter?

If you have impulse mags, does it seem to be harder to start after a heat soak?


IFP, do you know why you are supposed to start the front engine first in a 337?

[iflyforpie]

Yes.

[B-rad]

IFP, do you know why you are supposed to start the front engine first in a 337?

I don't know and would like you to explain it to me if you don't mind. The best I can come up with on my own would be for overheating issues. I did a quick search and most of what I saw mentioned starting the rear engine first for the benefit of being better able to hear and monitor the engine during start.

This manual suggests in the first paragraph that either one can be started first.
http://www.fsd-international.com/projec ... edures.pdf

[sidestick stirrer]

I thought that it was only necessary to lead with the aft engine during power-up on takeoff.
Never heard of starting the front engine first. Maybe it's to enhance cooling of the rear engine?

[tommywcom]

On my Seneca, I have tried starting the right hand engine first, but the result was the same (ie. right hand engine hard to start).

Incidentally if I start the easier-to-start engine first, would the alternator on that side generate sufficient electricity so cranking of the other side will not drain the battery?

[iflyforpie]

The reason they tell you to start the front engine first is its closer to the battery; same reason you typically start the right engine first on a King Air. But battery power is rarely a problem for me... overheating Sky-tech starters is. Without visual, audible, and tactile cues.... I find it just about impossible to start an engine, so back one gets started first.

The difference in heat between 30 seconds is nothing to write home about.

[Strega]

Tommywcom

Do you know what type of magnetos you have?

Where are you located?

[torquey401]

What exactly does "RH engine is hard to start" mean? Does it crank over slower? Does it spin just fine, but just won't catch? Much more information is needed to effectively troubleshoot.

That being said, I had a bad starter cable on a Seneca once and after it was replaced the engine cranked over properly. I cut open the cable to find corroded aluminum wires inside.

[tommywcom]

Tommywcom

Do you know what type of magnetos you have?

Where are you located?

I was told by my AME that it is an impulse coupling. I'm in the Vancouver area.

[tommywcom]

[quote="torquey401"]What exactly does "RH engine is hard to start" mean? Does it crank over slower? Does it spin just fine, but just won't catch? Much more information is needed to effectively troubleshoot.

It spins ok, but doesn't catch. It just spins, and spins, and spins, but that's it. Usually it takes a long time for it to catch, and once it does, it starts.

[DanWEC]

Is this warm or cold? The reason I asked about the primer kit earlier, was that if it's cool-ish, with the upgraded primer, the cold start procedure works every time.

Aux fuel pump on low, Prime for 3 sec, continue to hold primer and start cranking. While cranking bring throttle smoothly from full to idle repeatedly. After 3 seconds of this release the primer button while continuing cranking and moving the throttle, tapping the primer button for about 1 second every 5 sec.
After it fires and is running kill the aux pump.

Granted it shouldn't need this every time.. If it does and it isn't -20 something's up.

Cheers,
Dan

[GyvAir]

The reason they tell you to start the front engine first is its closer to the battery

I thought it was to scare the cows away from the fan at the back that you can't see very well before cranking..

Incidentally if I start the easier-to-start engine first, would the alternator on that side generate sufficient electricity so cranking of the other side will not drain the battery?

It will help, of course. Some manufacturers state that you should leave the alternators off until both engines are running, or at least not to crank the second engine while the running engine's alternator online, to prevent overloading charging system. No danger of course, in letting the alternator charge up the battery between cranking attempts.

If you have impulse mags, does it seem to be harder to start after a heat soak?

Waiting to hear the rest of the story on this question, Strega.

It spins ok, but doesn't catch. It just spins, and spins, and spins, but that's it. Usually it takes a long time for it to catch, and once it does, it starts.

If it just eventually catches while cranking and then runs fine, it sounds like it's simply either not getting fuel to the cylinders at first or it's getting badly flooded somehow before cranking and takes all that cranking to clear. (Typically with more fuel being added to the existing flood as we jockey the levers around and mess with the primer, trying to make something - anything - happen)

[Strega]

Strega wrote:
If you have impulse mags, does it seem to be harder to start after a heat soak?
Waiting to hear the rest of the story on this question, Strega.

If he has impulse mags, that when heat soaked, make the engine hard to start, it is likely weak magnets in the mags themselves, Usually when I encounter plane that starts hard when hot, and then look at the history of the mags, they are 25yrs plus old, and have never been apart for service/inspection.

Some other dumb questions to ask,, what kind of shape is the engine in? I once tried to prop a citabria with a O-235, and couldnt because the engine was soo worn out, you couldnt build enough compression to start it by hand on all 4 cylinders...

Also, are you certain the fuel servo is working properly? Seneca 1 should have Lyc Io-360...


Strega

[tommywcom]

Strega wrote:
If you have impulse mags, does it seem to be harder to start after a heat soak?
Waiting to hear the rest of the story on this question, Strega.

Yes, when the RH engine is hot, it is hard to start. But the mag was removed earlier this year and sent to a mag shop to get serviced so should be in good shape.

The RH engine has about 260 TSOH, about 13 years ago. Airframe has less than 5000 TTSN. The servo has not been touched.

On the other hand, the LH engine was sent away for a tear-down inspection with necessary parts replaced due to a light prop strike suffered before I bought it (but I was the one who sent it away). And the servo is new. The LH engine starts like a dream.

[Strega]

Did you have both mags serviced on the right engine? Usually only one has the impulse coupler, that one could still be bad...