Morning from the Pacific Northwest,
 
On MT: COACC page 32 the Fixed-Wing Engine Table lists the Basic Propeller as being TL 4 while the Airship Engine Table page 44 lists the Basic Propeller (Diesel) and Basic Propeller as TL 5.
 
My recollection and quick review of my books on hand and on the internet indicate the airships of the time used both diesel and aircraft engines which at least in my opinion would put them both at TL 4.
 
Should the Airship Basic Propeller (Diesel) and Basic Propeller engines be TL 4 versus TL 5 or am I out-to-lunch again?
 
Tom Rux