O-300 D engine compressions

Discussion in 'Maintenance Bay' started by Flybo01, Jun 14, 2019.

  1. Flybo01

    Flybo01 Filing Flight Plan

    Joined:
    Nov 11, 2018
    Messages:
    12
    Display Name:

    Display name:
    Flyby30
    hello folks

    So my aircraft engine (continental) is at TBO 2000hrs now with last 4 years of consistent engine compressions on all cylinders at 74 and above on all cylinders including engine oil analysis showing all green....now is going thru an annual inspection and according to this A&P the compressions are 70,70,60, 64, 70, 69.....I know this is still ok but why such of compression drop in 7 months since last checked? is he doing it correctly or is my engine starting to show signs of retirement.....he told me he ran the engine 45mnts then he checked the compressions....I’ve seen other A&P’s doing it on cold engines....when is the best reading....

    Thnk you
     
  2. Kenny Phillips

    Kenny Phillips Pattern Altitude

    Joined:
    Jul 29, 2018
    Messages:
    2,313
    Display Name:

    Display name:
    Kenny Phillips
    Geez, I wish "mechanics" would not call a differential cylinder pressure test a "compression" test. You can do both, and both should be done warm.