ATF3 Engineering and Design


NOTE:  It is a testament to the ATF3 engine design philosophy that no flight crew-member or passengers has ever been seriously injured of killed in an ATF3 powered aircraft accident since it first entered service with the U.S. Coast Guard in February 1982.  Unfortunately, one tragic fatality occurred when a security guard standing on the wing for better visibility was ingested into an ATF3-6A-3C Engine inlet after getting too close during high power ground runs.

    The ATF3 Turbofan engine is a three-spool, moderate bypass-ratio, high pressure-ratio design.  When the ATF3 engine was first designed in 1966 it was “state-of-the-art” although many modern design two-spool engines are capable of meeting the ATF3 design limits today.

    The ATF3 Engine has two modes of operation, Normal Mode and Manual mode.

NORMAL MODE operation is controlled by a full authority EEC (Electronic Engine Control).  The EEC will maintain all engine operating parameters within acceptable limits.  An added ATF3 benefit is the EEC locked throttle in climb and cruise feature, where the EEC reduces pilot workload by automatically adjusting Fan Spool Speed (N1) to maintain a constant ITT (Inter-turbine Temperature) in both climb and cruse.

MANUAL MODE (Backup Mode) in controlled by a power lever positioned mechanical governor located in the MFC (Main Fuel Control).  Maintaining all engine parameters within acceptable limits in manual mode operation is the responsibility of the Pilot/Operator.


    The ATF3-6 Turbofan Engine was certified under FAR Part 33, Amendment 6 on May 15, 1981.  FAA-LAX Engineer William C. Moring, and Garrett FAA-DER Arlen Larson both signed the ATF3 Type Certificate.




Basic Engine Dry Weight = 1124 Pounds (dependent on engine model and accessories)

Engine Bypass Ratio = 2.88:1 @ Sea Level Maximum N1 of the day

2.52:1 @ 40,000 Feet MSL & Mach 0.8 IAS

Fuel, Recommended =Jet A or JP-3

Oil, Recommended =Mobil Jet 254 or Mobil Jet 2

Engineering of The ATF3

    In this section, I would like to put the hard-core technical information, like thermodynamic cycle, component specs, materials used, tolerances, etc. I don't have any of that now, but I would like to build it as time goes on. If you would like to make any contributions, please email me.


Created 7/29/2008, Updated 4/13/2011