need part no. HELP

[Ernie Martin]

Working with Kim's information, I came up with something different.

For 73-76 models, the applicable figure is indeed 109, but my IPC doesn't show part 21 as S2289-3 (the S means it's a standard part made for many aircraft, not just Cessna). Instead, for those model years, it shows 1450024-1, which would make sense if it's a Cessna part with a metered orifice.

For your model, the 70-72 IPC has this as Figure 134, shown below. I've put the part numbers at the top right of the figure, and part 21 is also 1450024-1.

Kim (who I was fortunate enough to meet at our first Skymaster Fly-In at a Bahamian out-island in 2002) knows far more than me and it's my go-to guy when I'm having technical problems, so his answer -- not mine -- may be the right one.

Ernie