A.P. 129 RAF Flying Training Manual, Part I - Landplanes

[Crumpp]

Only in emergency or special operational conditions the aircraft is flow at the "maximum rpm/boost for level flight" (later called "all out") limits and not above.

Read above it.....


"rpm limitations are directly associated with similar limitations on boost pressures also defined in relation to the operational condition".........

(vi) It may only be exceeded momentarily during aerobatics, fighting manoeuvers, or when diving.