P28R Arrow performance numbers / MP & Tach

mandm

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Michael
I know I posted on here about this previously but forgot where the thread was.

I was mentioning that I wasn’t getting the performance numbers with the MP/Tach settings, so I have increased the MP about 1.5-2.5” and wa la, climb numbers even on hot days, IAS, is getting close to performance numbers expected.

On a hot day easily climbing at 500-700fpm (as opposed to 200-300fpm).

Cruise speed reaching 125-130kts IAS (as opposed to 110-115kts). My MP is now showing approx 26.5”MP / 2400 RPM (9-9.5gph) whereas before I had it at ~24”MP / 2400RPM (8-8.5gph) per the checklist (which per my calculation time vs fuel actually added was using I believe 7.6gph on average).

So I guess this means my MP gauge is off a bit, fuel flow is showing a little bit more than actual (which I’m happy with as it gives me a buffer), and now I believe my Hobbs meter is acting weird. The tach meter is integrated with the RPM gauge so I’m guessing these both either work or don’t? (Or can the tach time be faulty? - I think it’s accurate though).

Anyway, I’m happy to be getting those better performance simply by adding more throttle. And per some comments on here I am taking off and climbing with full power until about 700-1000’ AGL (which feels weird) but I’m getting to a safer altitude much faster than previously. And I’m also integrating “verify gear up” + “verify flaps up” as part of my climb and cruise mental checklist.
 
Have you ever checked your tach for accuracy? You can get an inexpensive optical tach and check it.

What does your MP guage read when sitting without the engine running? It should be around 30", less at higher altitudes.
 
Have you ever checked your tach for accuracy? You can get an inexpensive optical tach and check it.

What does your MP guage read when sitting without the engine running? It should be around 30", less at higher altitudes.
I’ll have a look next time
 
When there was a P28R Arrow in my club, I took it on several long trips, and I was never able to get book performance with it.
 
I’ll have a look next time
Btw, I’ve found a cool iPhone app for checking a tach…it will work right through the windshield.

It’s called “video tachometer” , in the App Store (its free). On the free version, you specify the rpm (from your actual tachometer) then aim your camera at the spinning prop. If the prop appears to stop, your aircraft tach is working/accurate.
 
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