PA-28 %power question

Merlinspop

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Sep 24, 2021
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Home base: KFDK
Good morning - a club member went flying today and reported back to me that at times the %pwr displayed looked off. He took one picture, I’ll try to attach it but here’s the particulars:
DA - 4754
OAT - 66f
RPM- 2560
FF - 12.8 gph
MAP - 18.6”
TAS - 118 (suggesting good power)

Looking at performance charts, I would expect %pwr to be around 72%, rather than the indicated 50%. It appears to me that the MAP is throwing off the calculation for %pwr.

Thoughts? Troubleshooting suggestions?
4ED34E6F-FD5D-45ED-8814-06D5670DA23D.jpeg
 

Spert

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Dec 26, 2020
Messages
41
Were you at full throttle when this was captured? If not, did the power indication change with throttle movement?
 

Merlinspop

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Joined
Sep 24, 2021
Messages
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Location
Home base: KFDK
Were you at full throttle when this was captured? If not, did the power indication change with throttle movement?
He said that he was not at full throttle. He had just leveled off from climbing out on a missed approach and was adjusting power for cruise when he noticed the reading. He said he could lower the percent power read out by reducing throttle further, but full throttle indicated no more than 50% at that altitude. He did not test if mixture changes made a difference.
 
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Spert

Member
Joined
Dec 26, 2020
Messages
41
He said that he was not at full throttle. He had just leveled off from climbing out on a missed approach and was adjusting power for cruise when he noticed the reading. He said he could lower the percent power read out by reducing throttle further, but full throttle indicated no more than 50% at that altitude. He did not test if mixture changes made a difference.
Take a look in the installation manual under Engine Information. It’s section 10.5 for the HDX variant. It talks about setup options and limitations you may see based on engine type.
 
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