Welcome Guest. Sign in or Signup

1 Answers

“Never lean using EGT when operating at more than 80% power.”

Asked by: 5936 views , , ,
Aircraft Systems, General Aviation

As a student pilot, I was reviewing my POH and recently came across the following sentence in bold print: "Never lean using EGT when operating at more than 80% power."

Why?  What would happen if I did lean using the EGT gauge at more than 80% power?

My fear is that I may deviate from the performace figures listed in the POH and unknowlingly run at more than 80% power.

Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

1 Answers



  1. John D. Collins on Mar 15, 2011

    You should follow your POH recommendations.  At high power settings, an extra rich mixture is used to help cool the engine and maintain an adequate margin from detonation occurring in the cylinders.  The higher power settings generate higher internal cylinder peak pressure, a rich mixture reduces the peak pressure.  Unless you have a turbo charged (or normalized) engine, 80% power can only be achieved below 6000 or 7000 feet.  If you have an EGT that shows a digital temperature number, if you note the EGT at full power on takeoff, it is usually OK to lean to that temperature as you climb. For most engines, the recommendation in the POH is conservative.

     

     

    On a turbo normalized engine such as the IO550N used in the Cirrus SR22TN airplane, they allow for two different methods of climb leaning, full rich at around 35 GPH or lean of peak at around 85% and 18 GPH upper limit.  However, they also note that the CHT and TIT (Turbo Inlet Temperature) need to be kept within acceptable bounds.  To cool the engine further, either lean to a lower fuel flow or go to full rich.  I only point this out to note that different airplanes with different engines have their own restrictions.

     

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes


The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.