Bendix drives.

I have a customer with a pair of factory reman IO 540s with less than 100 hours
on them. After landing he will sometimes find the bendix drives on the
starters partially and occasionally fully engaged. It does not happen every
flight but sometimes every other flight. On at least two occasions the bendix
drives were not engaged after shut down but were almost engaged when the pilot
returned from lunch an hour later! We have changed the starters twice now
since Kelly Aerospace admits too certain problems on some starters even though
these do not fall into the serial number range of those on a recent bulletin.

The bendix is supposed to be held back until the starter winds up and thrown
back in position when the engine speed exceeds the starter speed. So what is
going on here. One source doubts the starter motor is actually engaged as the
speed of the starter driven by the ring gear would through the windings off the
armature and ruin the starter. Is is possible some kind of transient voltage
spike at shut down is attempting to drive the starter? Why would an unengaged
bendix become engaged while the aircraft is shut down and the crew is at lunch?

On 12 May 2004 01:15:45 GMT, (JDupre5762) wrote:

I have a customer with a pair of factory reman IO 540s with less than 100 hours
on them. After landing he will sometimes find the bendix drives on the
starters partially and occasionally fully engaged. It does not happen every
flight but sometimes every other flight. On at least two occasions the bendix
drives were not engaged after shut down but were almost engaged when the pilot
returned from lunch an hour later! We have changed the starters twice now
since Kelly Aerospace admits too certain problems on some starters even though
these do not fall into the serial number range of those on a recent bulletin.

The bendix is supposed to be held back until the starter winds up and thrown
back in position when the engine speed exceeds the starter speed. So what is
going on here. One source doubts the starter motor is actually engaged as the
speed of the starter driven by the ring gear would through the windings off the
armature and ruin the starter. Is is possible some kind of transient voltage
spike at shut down is attempting to drive the starter? Why would an unengaged
bendix become engaged while the aircraft is shut down and the crew is at lunch?

Does the airplane have a firewall mounted starter solenoid? They are
installed specifically to make sure that when you release the starter
switch, no voltage can get to the starter to keep it engaged.

Corky Scott

On 12 May 2004 01:15:45 GMT, (JDupre5762) wrote:

I have a customer with a pair of factory reman IO 540s with less than 100
hours
on them. After landing he will sometimes find the bendix drives on the
starters partially and occasionally

fully engaged. It does not happen every
flight but sometimes every other flight.

snip

Does the airplane have a firewall mounted starter solenoid? They are
installed specifically to make sure that when you release the starter
switch, no voltage can get to the starter to keep it engaged.

From:

Yes there is a starter solenoid switch. Just yesterday we could see that on
one starter the bendix was retracted and could no be pulled forward with a
scribe. On the other starter the bendix gear was almost touching the ring gear
and could be moved back and forth. There is a pin and spring arrangement that
is supposed to keep the bendix gear retracted. Kelly Aerospace and Lycoming do
not know what is going on. The owner is thinking of going with Skytec starters
but needs the type that has a mounting ear for a propeller control bracket. 4
to 6 weeks from the factory at this point.

On 15 May 2004 01:05:00 GMT, (JDupre5762) wrote:

On 12 May 2004 01:15:45 GMT, (JDupre5762) wrote:

I have a customer with a pair of factory reman IO 540s with less than 100
hours
on them. After landing he will sometimes find the bendix drives on the
starters partially and occasionally

fully engaged. It does not happen every
flight but sometimes every other flight.

snip

Does the airplane have a firewall mounted starter solenoid? They are
installed specifically to make sure that when you release the starter
switch, no voltage can get to the starter to keep it engaged.

From:

Yes there is a starter solenoid switch. Just yesterday we could see that on
one starter the bendix was retracted and could no be pulled forward with a
scribe. On the other starter the bendix gear was almost touching the ring gear
and could be moved back and forth. There is a pin and spring arrangement that
is supposed to keep the bendix gear retracted. Kelly Aerospace and Lycoming do
not know what is going on. The owner is thinking of going with Skytec starters
but needs the type that has a mounting ear for a propeller control bracket. 4
to 6 weeks from the factory at this point.


make sure the bendix drive shaft is absolutely clean. it is one
component which should not have any lubricant on it at all.

After landing he will sometimes find the bendix drives on the
starters partially and occasionally

fully engaged. It does not happen every
flight but sometimes every other flight.

snip. Just yesterday we could see that on
one starter the bendix was retracted and could no be pulled forward with a
scribe. On the other starter the bendix gear was almost touching the ring
gear
and could be moved back and forth. There is a pin and spring arrangement
that

is supposed to keep the bendix gear retracted.

make sure the bendix drive shaft is absolutely clean. it is one
component which should not have any lubricant on it at all.

From: Stealth Pilot

I don't know about that. Lycoming recommends silicone spray lubricant. You do
not want too much lubricant or any type that will attract dirt that could turn
into gum or past that will bind the drive.

John Dupre'

I am curious... how does one determine that a bendix is "...almost
engaged" or "...partially (engaged)"?

Sid K

(JDupre5762) wrote in message
...
I have a customer with a pair of factory reman IO 540s with less than 100 hours
on them. After landing he will sometimes find the bendix drives on the
starters partially and occasionally fully engaged. It does not happen every
flight but sometimes every other flight. On at least two occasions the bendix
drives were not engaged after shut down but were almost engaged when the pilot
returned from lunch an hour later!
..........
Is is possible some kind of transient voltage
spike at shut down is attempting to drive the starter? Why would an unengaged
bendix become engaged while the aircraft is shut down and the crew is at lunch?

Visually or by touch.

Dave

sidk wrote:
I am curious... how does one determine that a bendix is "...almost
engaged" or "...partially (engaged)"?

Sid K

(JDupre5762) wrote in message
...

I have a customer with a pair of factory reman IO 540s with less than 100 hours
on them. After landing he will sometimes find the bendix drives on the
starters partially and occasionally fully engaged. It does not happen every
flight but sometimes every other flight. On at least two occasions the bendix
drives were not engaged after shut down but were almost engaged when the pilot
returned from lunch an hour later!

.........

Is is possible some kind of transient voltage
spike at shut down is attempting to drive the starter? Why would an unengaged
bendix become engaged while the aircraft is shut down and the crew is at lunch?