In article ,
Bertie the Bunyip wrote:

Is that the way the AD is written? Not specific to type? The 400s were very
varied machines and I doubt the spars were common to all of them..

Of course it's specific to type. The summary talks about "Cessna Aircraft
Company (Cessna) 100, 200, 300, and 400 series airplanes", but when you
read further down, you get to:

Applicability: All serial numbers of Models 150, 150A, 150B, 150C, 150D,
150E, 150F, 150G, 150H, 150J, 150K, 150L, 150M, A150K, A150L, A150M, F150F,
F150G, F150H, F150J, F150K, F150L, F150M, FA150K, FA150L, FRA150L, FRA150M,
152, A152, F152, FA152, 172, 172A, 172B, 172C, 172D, 172E, 172F, 172G,
172H, 172I, 172K, 172L, 172M, 172N, 172P, 172Q, 172RG, FP172, F172D, F172E,
F172F, F172G, F172H, F172K, F172L, F172M, F172N, F172P, FR172E, FR172F,
FR172G, FR172H, FR172J, FR172K, P172D, R172E(T41), R172F(T41), R172G(T41),
R172H(T41), R172J, R172K, 175, 175A, 175B, 175C, 177, 177A, 177B, 177RG,
F177RG, 180, 180A, 180B, 180C, 180D, 180E, 180F, 180G, 180H, 180J, 180K,
182, 182A, 182B, 182C, 182D, 182E, 182F, 182G, 182H, 182J, 182K, 182L,
182M, 182N, 182P, 182Q, 182R, F182P, F182Q, FR182, T182, R182, TR182, 185,
185A, 185B, 185C, 185D, 185E, A185E, A185F, 188, 188A, 188B, A188, A188A,
A188B, T188C, 206, P206A, P206B, P206C, P206D, P206E, TU206A, TU206B,
TU206C, TU206D, TU206E, TU206F, TU206G, TP206, TP206A, TP206B, TP206C,
TP206D, TP206E, U206, U206A, U206B, U206C, U206D, U206E, U206F, U206G, 207,
207A, T207, T207A, 208, 208B, 210, 210A, 210B, 210C, 210D, 210E, 210F,
210G, 210H, 210J, 210K, 210L, 210M, 210N, 210R, T210F, P210N, P210R, 210-5
(205), 210-5A (205A), T303, 310P, 310Q, 310R, T310P, 310Q, 310R, 335, 336,
337, 337A, 337B, 337C, 337D, 337E, 337F, 337G, 337H, F337E, F337F, F337G,
F337H, FT337E, FT337F, FT337GP, FT337HP, FTB337, T337B, T337C, T337D,
T337E, T337F, T337G, T337H, T337H-SP, M337B, P337H, 340, 340A, 401, 401A,
401B, 402, 402A, 402B, 402C, 404, F406, 411, 411A, 414, 414A, 421, 421A,
421B, 421C, and 425 airplanes, certificated in any category.