Hard landing vs. Landing hard

[hu]

Hello
I am looking some infromation about the hard landing (or high G force landing) vs. landing hard. Is there anyone can tell me where can I look at? many thanks

[Old Phart]

We asked Boeing to advise the recorded 'G' figure that would represent a Hard Landing. They responded to say that the Flight Recorder takes instantaneous values at a sampling rate of 16 times per second. This means that the recorded 'G' value does not necessarily co-incide with the maximum value that occured. There is therefore no way to co-relate a Hard Landing to a recorded 'G' value. They went on to define a Hard Landing as a landing which, in the opinion of the crew, was a Hard Landing.

In an airliner you would expect to see obvious signs such as baggage bins breaking open, oxygen masks deployed and so on. One aircraft reached the stand with the fuselage buckled just forward of the wing leading edge. The crew hadn't noted a hard landing in the log and, upon being shown the damage, they then entered it into the Technical Log as a 'Firm Touchdown' We don't know what the passengers thought...

[BigJETS]

I heard that sometimes ELTs can be triggered from a hard landing. Anyone else heard that?

[JEP]

BigJETS: A hard landing can start an ELT (at least on small planes like C172's).
I think 4 G or more will trigger the ELT, but I donīt remember exactly - maybe someone else has the figures.

ELT is short of Excellent Landing Tester - old joke - I know.

We always teach our PPL-students, to check the ELT by tuning the radio on 121.5, if they have made a hard landing, thus avoiding an unneccesary SAR-action.