BeechTalk - BT - C310 IFE

Username Protected · **Posted:** 11 Aug 2023, 20:20

[quote="Willis Robison"]sludge formation ususally comes from a non-ashless dispersant (Detergent) oil.
/quote]

Lead sludge is formed with any oil. The worst for sludge formation is Aeroshell 15w50, based on 30+ years of cleaning hundreds of crank bores during prop changes.

Username Protected · **Posted:** 11 Aug 2023, 20:29

Username Protected wrote:

2) Any thoughts on a restart in that situation? The initial post incident flight runup on the ground had everything performing normal. The preflight runup before the incident flight was also all normal. The a/c flew a 3-hr leg the morning of the incident flight with no issues. No issues/abnormalities on the morning preflight runup either.

Why would you restart it when you had no indication that anything had changed with the engine. In this instance I doubt I would have caged it, I probably would have diverted to the nearest airport with both running unless things got dramatically worse... that said, I'm not second guessing your decision, but once it was made why go back on it?

Username Protected · **Posted:** 11 Aug 2023, 21:31

Username Protected wrote:

sludge formation ususally comes from a non-ashless dispersant (Detergent) oil.
/quote]

Lead sludge is formed with any oil. The worst for sludge formation is Aeroshell 15w50, based on 30+ years of cleaning hundreds of crank bores during prop changes.

Username Protected · **Posted:** 12 Aug 2023, 14:57

As mentioned, the sludge is lead, usually from fuel blow-by past the rings of the cylinders. It builds up pretty quickly too. It really likes to build up in the bore of the nose of the crankshaft that feeds oil to the propeller for hydraulic control.

Oil doesn't get a lot of circulation there, and it acts like a centrifuge. Pull any constant speed prop that's been on for a couple hundred and you'll nearly always find sludge to some extent.

It's thick, grey, clay-like goo as has been stated.

The gasket to the prop governor has a screen built into, which is there to protect the governor from contamination by particles in the oil. It doesn't usually get sludged, but sometimes flakes of metal or carbon are found there.

Pulling props off is not a normal part of annual inspection, but honestly, a twin deserves scheduled prop inspections. A failure to feather when you need is a potentially fatal event. I kept a 5 year schedule for an IRAN of the props on my twin when I owned one. They do sometimes find corrosion or wear inside the propeller that otherwise seems to work normally.

Username Protected · **Posted:** 14 Aug 2023, 20:39

Username Protected wrote:

310 owner. I’m not buying the sludge as the root cause. Good job getting it home safe. I had one grenade on my 310, thankful for the 2nd engine.

I'm concerned that is not the cause either. Not sure what else would cause the issue. I feel like the lake of climb from 8k to 10k of 100-300fpm should not have been as bad if the prop was just not performing.

Username Protected · **Posted:** 14 Aug 2023, 20:49

Username Protected wrote:

2) Any thoughts on a restart in that situation? The initial post incident flight runup on the ground had everything performing normal. The preflight runup before the incident flight was also all normal. The a/c flew a 3-hr leg the morning of the incident flight with no issues. No issues/abnormalities on the morning preflight runup either.

Why would you restart it when you had no indication that anything had changed with the engine. In this instance I doubt I would have caged it, I probably would have diverted to the nearest airport with both running unless things got dramatically worse... that said, I'm not second guessing your decision, but once it was made why go back on it?

Username Protected · **Posted:** 15 Aug 2023, 14:30

Username Protected wrote:

All good. I am here for the second guessing. I think about a restart because the engine instruments were normal (other than surging RPM). If the other instruments are in the green, then a restart may have given me my second engine back and been a safer divert. I've always learned a rule of thumb is to restart unless it is fire, fod, or friction.

I shut it down because I was not sure if a surging/uncontrollable prop could lead to a more catastrophic event. I still do not know if it could. Any feedback on that leading to a more catastrophic event? I am not convinced it was the best decision - I'm here to learn from the brain trust. I appreciate your insight.

In a twin, shutting down a surging prop is a good idea. Assuming, Mr. Pilot-Guy is up to date on recent training for engine-out operations.

In a single, you sweat it out till you make the runway and hope you can keep thrust till you get there.

C310 IFE - Surging Prop 12 hrs after Annual