Yes it was a common thing on the TB20 that the RSA fuel servo was set up for a too-low fuel flow. I used to have 22GPH. There isn’t much leeway on a legal job to go high but setting it for the very top of the permitted band gives you about 25GPH. I think all the factory installations were done too low; presumably by Socata or some local shop they used. This makes a big difference to climb CHTs but of course doesn’t change the cruise fuel flow.
Never mind the CHTs, with not enough full rich FF you might not be making full TO power. Not really limiting at Zurich, a superb airman such as Peter will know something is not right and have plenty of space to abort the TO, but might be elsewhere, or to a lesser pilot.
Actually, it is the other way around: CMI wanted more power on the IO550 series and reduced the fuel flow at max power to compete with the IO540.
This setting is not good for engine health. If the engine is set up properly, you can gain a few % of horsepower by slightly leaning for a few dozen seconds until clear of the obstacle, at the same time you will see the CHTs rise.
A very rich mixture slows down the flamefront and lowers CHTs at the expense of power.
No hole in the crankcase. Good.
a superb airman such as Peter
I don‘t feel like being that. Maybe regarding the pilot skills itself, but not at all regarding the technical aspects. I do have to trust the maintenance guys, because I do understand not enough about the technical things to proof myself if it is right what they are saying or not. So therefore I‘m very happy about all the advices here to ask the right questions when taking back the plane before the takeoff run. Thanks @dirkdj to open up the discussion about the fuel flow.
Meanwhile I got photos from the propeller overhaul and I was shocked again. They inserted too much grease during one of the last maintenances and this might have caused some vibrations and could be one reason for some of the minor oil leakages when flying the propeller full power on climb. How could I know and how to avoid, that the technicians make mistakes in future? I have no clue at all.
Was this prop opened by the same company which did the last work?
I have just asked a colleague who is a qualified prop shop A&P and he agrees there is too much grease. This should be common knowledge.
Was this prop opened by the same company which did the last work?
No, it was opened by the company who does the overhaul and they asked me to send the pictures to my maintenance organisation.
How do you get too much grease in there? Isn’t the process to remove the opposing greasing nipple and pump grease until clean grease comes out on the other side?
From the PA-23 service manual, section 2-90. APPLICATION OF GREASE.
“Use extra care when greasing constant speed propeller hub to avoid blowing clamp gaskets.
Remove one grease fitting while applying grease to other fitting until fresh grease appears at hole of
removed fitting. Uneven greasing effects propeller balance.”
For Hartzell, to avoid the hub filling up with the grease during service, for each blade shank there are two grease nipples. One of the nipples for each blade shank has to be removed and the grease to be pumped in as advised in the propeller service book.
So the central hub cavity does not fill up with grease. Whoever did that job must have used one of these
