Ray Jay Losing Boost

[M20F]

Since I got my M20F back from annual and upgrades it will only develop 3-4 inches on the Ray Jay which worked great on the trip down.  We hooked a vacuum up to the exhaust today and the only leak I could find was coming from The EGT probe on the #4 cylinder which was installed along with an EI MVP-50.  It wasn't a major leak but does anyone know from experience if this could cause that much loss of boost?

We are having issues with the new Skytec starter (fairly certain at this point it is a dude) so couldn't see if that fixed the problem.  Goes into the local MSC on Monday but interested in opinions.

[Antoni Deighton]

I guess that happens after breaking up with Kim Kardashian!  Oh, wrong Ray J, sorry! ;-)

[m20exec]

Quote: M20F

Since I got my M20F back from annual and upgrades it will only develop 3-4 inches on the Ray Jay which worked great on the trip down.  We hooked a vacuum up to the exhaust today and the only leak I could find was coming from The EGT probe on the #4 cylinder which was installed along with an EI MVP-50.  It wasn't a major leak but does anyone know from experience if this could cause that much loss of boost?

We are having issues with the new Skytec starter (fairly certain at this point it is a dude) so couldn't see if that fixed the problem.  Goes into the local MSC on Monday but interested in opinions.

[M20F]

New starter fixed the starter problem and the boost loss was related to the hose going from the air filter to the airbox that the turbo also feeds into.  Hose was on but the clamp was not tightened at all which we didn't notice till we dropped the bottom cowling.  Good to have a working airplane again!

[m20exec]

I think this comes under the category of oops! Is that a scimitar prop on your F?. I considered one for my AC, but the engineers at Hartzell were less than enthused with it being installed on a TN M20 as they hadn't done any flight testing in this configuration.

[M20F]

Hi Craig yes it is and haven't noticed any issues with it in the year I have had the plane (the prop was part of the purchase arrangement).  I can't comment though on before/after performance.

[m20exec]

Hi Michael -- I was considering the scimitar 2 blade after the Hartzell hub AD was issued. At that time Hartzell was offering a substantial discount on a new hub and/or propellor. The discounted price for a new propellor was $5700 and the price for the top prop was around $7k, but that price included a new bulkhead and spinner. I spoke at length with Mike at Hartzell about that prop and he was highly recommending it until I informed him I had a Rayjay installation. After he learned it was going a TN M20 he said he wanted to run it by the engineers first. He contacted me later and said the engineers wouldn't condone this conversion as the turbo might impact the harmonic characteristics. While I didn't interpret this to imply there would be any issues, this combined with a different RPM restriction was enough to dissuade me so I ended up with a later revision of the standard prop. Mike did say that if there were a sufficient number of TN owners interested they "might" re-test with a TN M20. As my only knowledge of this was in the late part of 2007 I have no idea if Hartzell ever did this. While I have little doubt the scimitar prop is a better design, unless Hartzell has test data with a TN M20 it's simply less of a known quantity having only been flight tested with a normally aspirated F. A grey area might be how this would impact the Rayjay STC. If an incident were to occur an insurance carrier not wanting to pay might argue the propellor didn't conform with the Rayjay STC. While I wouldn't lose any sleep if I had this combination I'd be curious if Hartzell has changed their guidance regarding this.