R2800 combustion starter

[greatgonzo]

I wonder how the problem of hydraulic block was dealt with, when combustion starter was used?

[shrike]

Whether by electric start, or cartridge start, you always turn the prop by hand before starting.

[greatgonzo]

Right. Thank You.
Still I was curious, was there any safety system like clutch built in electric starter.

[flightsimer]

Whether by electric start, or cartridge start, you always turn the prop by hand before starting.

Not entirely true.


Our C-123, which has R-2800's, has an electric starter on it that instantly disengages via a clutch the moment a stopping force is applied, such as in a hydraulic locked cylinder.

When we preflight the aircraft, we motor the engines to check the cylinders, we do not pull them through by hand. This I believe was also the standard procedure used in the service as I recall it being in the C-123 Dash 1.

Now if we do have a lock, which has occasionally happened in the past, then we have to pull the prop backwards just like everyone else or remove a spark plug to drain the cylinder.

Our C-47, which has R-1830's has the same type starter as well.

[Matt Gunsch]

I went thru some of my old handbooks and cannot find anything about clutches on a coffman starter.

The reason you don't pull the props thru on the 123 is you cannot reach them, same as the C-119, and PBY, HU-16 and others.
That said, I always pull props thru on those that can be done, and to rely on the clutch on a starter is asking for trouble, how do you know the clutches were set correctly at the last overhaul ? I ran up a C-47 and about 3 hrs later I was going to do another run, the owner said we did not have to pull it thru since we had run not long ago, well I pulled the right engine thru and within 3 blades I had a hydraulic lock. When you do come across a hydraulic lock, pull the plugs and drain the oil, NEVER EVER pull the backwards and then try to start, the oil had to go somewhere, there is always the chance the oil went back into the intake and will get pulled back into cylinder.

[flightsimer]

I went thru some of my old handbooks and cannot find anything about clutches on a coffman starter.

The reason you don't pull the props thru on the 123 is you cannot reach them, same as the C-119, and PBY, HU-16 and others.
That said, I always pull props thru on those that can be done, and to rely on the clutch on a starter is asking for trouble, how do you know the clutches were set correctly at the last overhaul ? I ran up a C-47 and about 3 hrs later I was going to do another run, the owner said we did not have to pull it thru since we had run not long ago, well I pulled the right engine thru and within 3 blades I had a hydraulic lock. When you do come across a hydraulic lock, pull the plugs and drain the oil, NEVER EVER pull the backwards and then try to start, the oil had to go somewhere, there is always the chance the oil went back into the intake and will get pulled back into cylinder.

Agreed, no reason to chance a $50k+ engine if you don't have to.

I wonder where the heck I got pulling the engine backwards from. Never have experienced a hydro lock myself and when we have had one with the 123, I was not there to see it cleared. I can only remember two times of us having one in the five years I have been with the museum. But you learn something every day... I'm not really on the mechanical side of things, but i'm trying to get there...

[famvburg]

Many years ago when I worked on round motors (R-985s and R-1340s) and also had a Queen Air with the big ol' geared Lycomings on her, all 3 types could use the same starter, EXCEPT, the clutch setting had to be different for the different radials, i.e., if you put the one torqued for the -1340 on the -985, it would power its way thru a hydro lock, whereas the one set for the -985 might not turn a -1340 adequately. As for the setting when it was used on the Lycoming, I don't have a clue. I think all of this is correct, but I won't swear to it, I do know the starters have clutches so technically they will kick out in the event of a hydro lock but why risk the damage if you can do a manual pull-thru.