Heavy Landing
 

Hi everybody,

does any of you know what's the parameter which defines an heavy landing (technical inspection required) on a JAR25 aircraft? I've read somewhere that it's when v/s on touch down is above 630 ft/min, is this statement correct?
Thanks!

Don't about JAR, but FAR part 25 criteria require that landing gear design be based on:

-A sink rate of 10 feet per second at the maximum design landing weight

-A sink rate of 6 feet per second at the maximum design takeoff weight.

So 630'/min seems pretty much correct, at least in FARland.

FB

FAR 25 doesn't define what a hard/heavy landing is. It only provides minimum design requirements: 10 fps up to MLW, 6 fps from MLW to MTOW.

The hard/heavy landing criteria should be defined by the manufacturer for your aircraft type. This definition can be based on the FAR 25 design requirements, but this is not necessarily so. Some manufacturers include runway excursions and other things (such as one main impacting well before the other(s)) in their definition of hard landing. Some manufacturers define heavy landing as any landing above MLW. It really depends.

I would caution against relying on the design requirements for a complete definition of hard or heavy landing.

On another note, if we're going by the FAR 25 regs, then 630 fpm is definitely not "pretty much correct". 630 fpm would be 10.5 fps and would probably be classified as a hard landing. Remember that landing energy increases with the square of descent rate, and your margin between limit and reserve energy condition is only 2 fps (reserve energy per the FAR is 12 fps). An extra 0.5 fps makes quite a difference under the circumstances.

My a/c "Line maintenance manual" has a nice little graph of vertical acc vs mass. The higher the mass, the lower the "g" treshold for a special inspection...

on the 744, it's around 1.9g

Who said that FAR 25 define what a hard/heavy landing is? I wrote about landing gear DESIGN, and in any case what I wrote is exactly copied from a Boeing publication on overweight landings.

Definitely is, the difference is just 30 feet, 5%...enough to justify the words "pretty much", otherwise would have said only "correct". The original question was just that...the limit of heavy landing, and 630'/min is badly close to that limit (if it is a limit).

Krujje, please, next time better reading. :ok:

FB

Fullblast, your answer to the question sounded to me like you were implying that FAR 25 provided a definition of hard/heavy landing, thus my response. Sorry if you took offense.

No, definitely wrong. The difference between 10 fps and 10.5 fps to an aircraft is more than you seem to think. It is not just a question of 5%. The words "pretty much" make it sound like it is okay, which it may well not be. To lead somebody to think otherwise, especially on this forum, could be dangerous. You need to be careful about making statements like this.

Not sure about the definitions but the folks at My Travel might have a few clues!

http://www.aaib.gov.uk/cms_resources...JZ%2012-08.pdf

Depends on the type.

My airline, for Boeings (744 and 777) it is 1.9g, but for the bus (330 and 340) it is 1.6g.

That's high for the 744 ours is 1.6 or 1.7 depending on the data sample rate!

In a previous life I worked as a LAME at a terminal transit checking aircraft. The DC8 50 series had what we called the "lie detector" on the MLG struts. It consisted of a thin Al strip clamped to the bottom of the oleo inner cylinder pointing up. If it was bent, there'd been a heavy landing and a check was required. Conversely, if it was still straight there had been no exceedence.

Saved any arguments. :ok:

Our planes (737 classics and NG) did print a hard landing report if the touchdown g load was higher than 1.9g, an inspection was necessary when it was higher than 2.0g which is consistent with the allowed g-loads (0 to 2 g with flaps down, -1 to 2,5 g with flaps up).

Whenever a report was printed an ASR and techlog entry were mandatory.

There is a graph in a QAR or miniQAR recording the g level at touchdown. So even when not reported engineering can see the evidence if your a/c have these.

On some aircraft (at least on the MD11 that is), the bank angle during touch down plays an additional role:

The higher the bank angle during touch down, the lower the g-load that triggers the hard landing report. :uhoh:

If your flying a modern aircraft - Airbus or Boeing - chances are that you'll know that it was in fact a hard landing by the time you reach your parking gate.

ACARS will have automatically sent a report to your OPS and MCC. The Head of Engineering will be the guy with the weary look on his face waiting to greet you.


Cheers

Many years ago I flew BAe Jetstream 31/32 aircraft that had nylon 'cable tie-wraps' fitted around the bottom of the MLG oleo; thus, if the tie-wrap was deformed (squashed flat by full compression of the oleo) then a heavy landing had ocurred. I have no idea who decided that that would define 'heavy landing' but presumably (!) someone calculated that full oleo-compression equated to a valid heavy-landing trigger. In my experience, the BAe31 was not easy to land well consistently, but in six years I never got to see the theory tested.

Boeing synopsis : Any contact with a landing surface or otherwise(ditching etc)with a G load in excess of 2.0G's constitutes a "Heavy landing".
No such thing as a "Hard landing" in Boeing terminology!
All heavy landings require a boroscopic/xray examination of all load bearing/stress sharing structures.
And thats from Ch AME Boeing at the Renton plant.
Happy New Year all......:ok:

Flaperon, thats not quite correct either. Boroscopic inspection is not required on Boeing inspections (usually engines only) for a phase I check.
The maintenance manual specifies phased checks for heavy landings. If damage is found on phase I then a more detailed inspection is required. If no damage found then the inspection is complete and the aircraft released to service.Phase I involves visual checks, with phase II involving fairing removal etc....(Boeing)
X-Ray inspection etc is done for components removed and taken to workshops,

What is the procedure like for a hard landing inspection ? And i've heard that some a/c have fuse pins that can be checked visually on the MLG if the design max load has exceeded ? Where are they and how do they look like ? Pics ? Is the purple round thingey on the MLG of newer airbus 320s and 330s one of them ?

Hard or not to hard
 

Boeing has here the nice thing to let the pilots decide.
Original AMM B777

2) The pilot must make a decision if a structural examination is necessary.
(a) The AMM thresholds are intended to aid the flight crew in making their decision, not replace the flight
crew's judgement of a hard landing. Boeing has no objection if an operator, at the operator's discretion,
chooses to use the AMM values and FDR data to trigger a hard landing inspection in addition to flight
crew judgement.

Airbus is there really strict.
Limit is e.g.A330 Delta g from >1.2g (minimum g-load to maximum g-load in a special timeframe) and lowering rate from 14 ft/s for the all in one inspection....
first entry point is a detailed visual inspection, than it depends on findings.

But anyhow dear pilots :ok:, I got both loadreports downlinked :D

Hard landing
 

A hard landing is when A pilot reports one. There is no other indication other than physical damage. Alot of pilots will not report hard landings for obvious reasons. The only way to determine how hard, is by doing a dfdr dump.