252 and Encore pilots - ground run-up/ignition/mag check - leaned?

[nationwide]

On 6/11/2020 at 9:45 AM, kortopates said:

750 rpm is too high, fuel pressure goes up quickly with rpm. if you got 15 psi at 750 it will be lower at 700, but you won't know how much till you check it.

No noticeable rise at 700 while leaning to ICO is a problem. 

The log entry was referring to max FF of 31 - but using unmetered fuel pressure for max FF is wrong  (see note 2 below table - its for reference only and 31 is on the low side!) - it has be metered fuel pressure. The mechanic obviously does have the right equipment to properly set up the fuel system. But if you have confidence in your FF being accurate, which it should be, then I'd personally prefer to set up max FF using your ships FF - TCM approves of this (see note 4 below). But not using unmetered pressure - especially on a turbo.

Be careful not to change metered low pressure till you have the help to adjust all the fuel setup parameters - Idle at 700, low pressure idle metered pressure, idle mixture and metered max fuel pressure/max FF. Change the low end and it can effect the high end and vice versa, it an iterative process till its very small tweaks.

Improper fuel system setup is the #1 anomaly I see new turbo owners have and often while they're trying to ferry the aircraft home after purchase. Unfortunately it can lead to high temps and partial power losses right at a time when a new owner has no idea what to expect of their unfamiliar engine. The best advice I can give for TCM engines is abort any takeoff when TIT exceeds 1450F on the takeoff run.

Paul, my shop is having trouble setting up the fuel flows.  After much futzing back and forth (7+ hrs labor that particular iteration...) it was basically working ok but was too rich at high power (FF >29 and rough, staining at exhaust).  I had them correct it and now it’s a mess.  Won’t even start right.  The unmetered is way down near 5.9 or 6, which is too low (unmetered min 6.25) but they say they are having settings migrate between days and even run ups on a day.  They want to overhaul my pump.  TCM is concurring with their opinion.

I did read somewhere that inability to get constant results may be a sign of pump problems (aneroid issues, etc.).  Do you concur?

[kortopates]

23 hours ago, nationwide said:

Paul, my shop is having trouble setting up the fuel flows.  After much futzing back and forth (7+ hrs labor that particular iteration...) it was basically working ok but was too rich at high power (FF >29 and rough, staining at exhaust).  I had them correct it and now it’s a mess.  Won’t even start right.  The unmetered is way down near 5.9 or 6, which is too low (unmetered min 6.25) but they say they are having settings migrate between days and even run ups on a day.  They want to overhaul my pump.  TCM is concurring with their opinion.

I did read somewhere that inability to get constant results may be a sign of pump problems (aneroid issues, etc.).  Do you concur?

That's very true, in ability of the pump to hold settings is common reason to need to send it out to a repair station for overhaul, due leaky seals.

Also, make sure you no longer have the bronze but newer steel lever arm attached to the pump when you send it in,  else request they also send you the new steel mixture lever arm that your mixture control attaches too. This was the subject of a TCM SI some years ago that could leave you with an inability to adjust mixture in flight. Last time I saw this priced it was about $120 some years ago. I don't recall the SI # but its an important one, but will be in your log book if you did comply. When it comes back though, it'll still require all the low-high adjustments but should be pretty close.

Edited February 25, 2021 by kortopates

[xavierde]

I got this pump overhauled last Summer, wasn't cheap but helped with hot starts which are much easier now. The shop sent it to Aircraft Accessories in OK and their turn around time was relatively quick.