Originally Posted by
AMDEC
LTE was used by US Army to designate unanticipated yaw, when they had the problem in the 80's, mainly on OH-58. Bell already noticed in a Service Letter dated July 1984 that the term was misleading.
FAA used the LTE wording in AC 90-95 as a synonym of "unanticipated yaw"
Do not mind what Loss, Tail Rotor and Effectiveness mean, LTE is only a synonym of "unanticipated yaw". I cannot imagine that FAA, as a Certification Authority, would consider certifying a rotor that could lose efficiency and, to my knowledge, nobody has ever demonstrated such a phenomenon.
Before LTE, "Tail Rotor Stall" was used... untill they demonstrated that no stall occurred. But they replaced a myth by another one, because nobody remember the origin of LTE. This is why many think, erroneously that it designates a loss of effectiveness of the tail rotor that does not exist.
If you understand LTE (as it is presented in the Rotorcraft Flying Hanbook) then there really should be no such thing as "unanticipated" yaw.
In other words, if I understand that getting below ETL in a left quartering headwind will cause the nose to want to yaw right, then I will be prepared for it, with left pedal ready to go.
Anyway, that's how I look at it in FAA land.
,...but yeah, the words themselves don't represent the condition very well.