Welcome Guest. Sign in or Signup

5 Answers

Run up

Asked by: 3705 views Aircraft Systems, Flight Instructor

On take off, c172. W/ a 160 hp engine only got to 2200-2400 rpm from sea level airport. By time we reached 2500-2750f ft rpm had risen to 2500,  never reaching near red line of 2700 rpm.  Next take off was the same, never getting close to red line. Static run up on the ground gave max rpm of 2200- 2400 rpm. What actions should be taken? Some have told me this is normal, I remember more power on takeoff, and I'm concerned.

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.

5 Answers

  1. John D. Collins on Sep 15, 2012

    Could be normal or not. Look in your POH Limitation section. It will list the engine and propeller. Cessna also provides a note in the Power Plant Limitations section that specifies the static RPM range, but this is not the same for all C172’s. For example, a 1983 172P, it is 2470 to 2570, for a 1979 172N, it is 2280 to 2400. They both produce 160 HP, but have a different engine model and propeller. Look it up in your POH.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

  2. Nathan Parker on Sep 15, 2012

    If a C172 got max RPM while not moving, then the RPM would continue to increase as the airplane velocity increased, and it would quickly exceed red line. This is the reason why constant speed props improve takeoff performance. They can reduce the prop pitch at low airspeeds, allowing max RPM, and then increase pitch as the airspeed increases to prevent over speeding.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes

  3. Jim Foley on Sep 15, 2012

    Since John and Nathan have covered the technical, I’m not gonna comment on that again. I will say, however, that if you feel something is wrong during run-up and takeoff, you should have aborted and ask maintenance about it. If it’s a big enough concern then it would be terrible ADM and dangerous to continue the take-off. I know I would not fly with somebody who has concerns about the aircraft, yet chooses to fly anyway.

    -1 Votes Thumb up 0 Votes Thumb down 1 Votes

  4. Bob Watson on Sep 16, 2012

    That sounds about like the C-172 I flew recently and seems normal, to me. But like Jim said, what I think doesn’t count for much. What counts is what you think and if that seems safe.

    As a way to doublecheck, find what the takeoff performance should be in that plane (and loading, and weather) and see if you get an experience similar to what the book says.If the POH says you should be off the ground in 1,000′ and you’re not then you should be concerned. If you are then its probably just fine.

    0 Votes Thumb up 0 Votes Thumb down 0 Votes

  5. Naaman Beck on Sep 19, 2012

    The other thing that you need to consider is the temperature. You said your airport is at sea level but that doesn’t mean your density altitude is going to be that low as well. Like Bob said look at the performance section and also think about leaning mixture procedures.

    0 Votes Thumb up 0 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.