Steve Pierce said:
If you have a 125 hp Super Cub which is designated PA18 do you need an STC to install an O-320? It is in the mid 600s serial number which means it has the double groove trim system and already has Clevland wheels and brakes. They are on the same type certificate and I would think if you met the criteria shown in the parts manual it would be a no brainer but I also know that Cub Crafters has an STC for the same.
You need a STC or field approval...
Engine
Models PA-18 and PA-19:
Continentals C-90-12F, or C-90-8F (Uses carburetor setting No. 530726)
(
See Item 106 for models PA-18 "125" and PA-18A, Item 108 for Models PA-18 "135" and PA-18A "135", and NOTE 3 for Model PA-18 "105" (Special)) (
See also Items 101, 106 and 108 for optional engines)
101. Lycoming O-235-C and -C1 engine (Eligible only
when installed in accordance with Piper Dwg. No. 12447)
(See also NOTE 3)
Fuel - 80 min. grade aviation gasoline
Engine Limits - For all operations:
O-235-C: 2600 r.p.m. (100 hp)
O-235-C1: 2600 r.p.m. (108 hp)
Oil Capacity - 6 quarts at (-36)
Required Equipment Items:
(See Item 2 for propellers)
With Lycoming O-235-C engine:
Landplane and Skiplane: Items 401(a), 401(j) and 601(b).
Seaplane: Items 401(i)
With Lycoming O-235-C1 engine:
Landplane and Skiplane: Items 401(b) and 601(b).
Seaplane: Items 401(c).
106. Lycoming O-290-D engine. Install in accordance with
Piper Dwg. No. 12447.
Fuel - 80 min. grade aviation gasoline
Engine Limits - For all operations, 2600 r.p.m (125 hp.)
Oil Capacity - 8 quarts at (-36)
Items 104, 601(b), and 401(f), 401(g) or 401(p) are required.
(See Item 3 for propellers.)
108. Lycoming O290-D2 engine. Install in accordance
with Piper Dwg. No. 12447.
Fuel - 80/87 min. grade aviation gasoline
Engine Limits - For all operations, 2600 r.p.m. (135 hp.)
Fuel Capacity - 36 gallons at (+24)
Oil Capacity - 8 quarts at (-36)
Items 102 and 109 are required.
See Item 4 for propellers.
