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Mammoth Freighters LLC (Mammoth) was founded in December of 2020 by two top cargo conversion program executives – Bill Wagner and Bill Tarpley – specifically to design, develop, convert, and support the development of passenger to freighter conversions.  The launch type is the Boeing 777 (both the 200 LR and 300 ER variants).  The Mammoth converted 777 is one of the most productive and economical 777 long range freighters in the world.


Mammoth, a Boeing Licensee for the Boeing 777, is developing a global production and conversion site network which will include its Ft. Worth, Texas,-based Aspire MRO Facility as well as additional conversion capacity planned at three other sites around the world. 


Mammoth is backed by private investment funds managed by Fortress Investment Group LLC and its affiliates. Mammoth is based in Orlando, Florida with engineering offices in Escondido, California and Seattle, Washington.

Our People


William (Bill) Wagner

Wagner is the President and owner of Wagner Aeronautical, where he is responsible for all business and engineering aspects of the Company.  Wagner began his career as a stress analyst at Boeing and has worked at other major aerospace companies including Northrop, Lockheed, Flight Structures, Inc. and Teledyne Ryan Aeronautical.  Wagner is an FAA certified structures Designated Engineering Representative (“DER”) with authorization in four specialties including static, fatigue, fracture analysis and repairs and alterations.  Wagner has been directly involved in the development of several major conversion programs including the “nose-to-tail” STC development for the 727 and 757 aircraft as well as STC work for the 747 Combi conversion and the 737, A321 and 767 STC development.  Wagner has worked extensively with the FAA over the last thirty years and has secured an FAA approved finite element model (“FEM”) methodology, provided FAA FEM training and provided the FAA with guidance on freighter conversion compliance and methodology.


William (Bill) Tarpley

Tarpley has over 35 years of freighter conversion experience including 20 years at Boeing as a design engineer and program manager of the DC-10, MD-10, and 767 freighter conversion programs.  Following his time at Boeing, Tarpley was the Chief Operating Officer at ATSG’s freighter leasing company, Cargo Aircraft Management, Inc (“CAM”), where he oversaw the acquisition, conversion, management, and leasing of over seventy 767 and 757 P2F conversions.

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