For engineers -- When a bad landing a heavy landing ??

[Jet A1]

Hi guys - just out of interest, on my gizmobus we can print out every landing trace with touchdown G - At what point is it deemed to be a heavy landing requiring a check ?

[Winkiepinkie]

Just out of interest eh? oh go on, tell us what happened...

[r304ndy]

According the Airbus AMM Chapter 5, a hard landing means, for aircraft greater than 240T,:

- Nz is greater than 1.6g

or

- descent rate equal to or greater than 9ft/s

Note that a hard landing is different to a heavy landing.

[FlightDetent]

Not an engineer.

My hardest so far was 1,89 g and sure it was positive. Company limit for having a talk (no biscuit served neither tea here :\) is 1,9 :uhoh:. However I've been told once the tech limit would be 2,4g.

On the other side, for overweight landing, a pound extra is already too much and checks are required.

Fly safe,
FD.

[r304ndy]

Apologies, let me correct one of the values quoted in my earlier reply.

A hard landing is defined as:

- a landing with Nz of more than 2g at the CG, not 1.6g


An overweight landing is defined as a landing at more than the MLW with Nz of more than 1.6g, or a landing at more than the MLW with Nz of more than 6 ft/s.

[BigHairyBum]

Its also at the captains discretion.

Heard of one skipper reporting a heavy landing to the engineers who said it was beneath the g requirement for a heavy landing check. But, surely the guy who felt it should have some say?

Maybe just OOOOOOFFF!!!:\

[DDG]

Our company proceedures reflect the Aircraft Maintenance Manual for the B737NG in that The Captain will decide if a hard landing Phase 1 inspection is required.If any damage is found by the engineer the PHASE TWO inspection is to be carried out which includes a DFDR download to see how hard it hit the ground,depending on the G`s what is inspected.

Heavy landings inspection require the captain to inform of normal/medium/heavy sink rate with possible DFDR download to confirm the extent of inspections

[Blacksheep]

We had to work this one out for ourselves when one of our customers seriously bent a B767 fuselage in what the pilot, when challenged, described as a "firm touchdown". The pilot had declined to make a tech log entry despite the evidence of a severely distorted fuselage.

In the subsequent argument, conducted while Boeing carried out seven million dollars worth of repairs, we were asked to get the touchdown 'G' from the DFDR. The recorded vertical acceleration was a mere 1.98G so we asked Boeing for a clear definition of a hard landing in terms of 'G'. Boeing replied that, as the peak value is a spike of very short duration compared to the sampling rate of vertical acceleration, there is no way of determining actual vertical acceleration at impact from a DFDR readout. Boeing therefore define a hard landing as a landing which, in the opinion of the crew, is a hard landing. Signs of damage may also help in determining the classification.

In view of the extent of the damage we therefore had no hesitation in re-classifying the reported firm touchdown as a hard landing, despite the relatively mild 'G' figure. The fact remains that there is no known method of extracting the true peak value of vertical acceleration from a DFDR readout and such readouts cannot be relied upon to determine the need for a full hard landing check i.a.w. the Maintenance Manual.

Engineers and aircrew are obliged to use their judgement.

[mustafagander]

Back in "the good old days" the DC8 50 series had a little Al strip clamped to the bottoms of the main gear shock struts, pointing up. If said strip was bent, there had been a heavy landing - end of discussion. Very useful for us LAMEs doing a transit check. We nicknamed the strips lie detectors :ok:

[chuks]

Back when I was driving a bug-smasher out of Miami International I used to gawk at the heavy iron that was coming in for maintenance at a facility next to my ramp.

One that caught my attention was a 727 with such a set of wrinkles along the lower fuselage behind the nose gear that they were quite obvious to the naked eye from a distance of about 20 feet. The aircraft belonged to a military-operated civil airline from South America and I was told it had been flown in for a routine check when some sort of 'Wrinkles? What wrinkles?' conversation ensued. Turns out someone was late on the round-out but didn't bother making a report. They ended up scrapping the aircraft as uneconomical to repair.

And in Nigeria (where else?) a BAC 1-11 had been slammed back on the runway when the stickshaker actuated after liftoff, going deep into the over-run on 19L and then being simply dragged out of the bundu, cleaned off and put back in service. Some time later they found a rather large crack in a wing spar so that the airplane was scrapped.

[catpinsan]

in our outfit the captain reports what he thinks is a hard landing - engineering then checks the data readout to detirmine the actual 'g' value and v/s at touchdown, dependind on these the actions (or lack of) are given in the maintainance manual

if not reported, 1.5g and above throws up a flag during routine dfdr analysis, 1.8 is cause for a chat. mitigating factors such as a well stabilised approach maybe taken taken into account before calling for a chat.

in my experience, anything much over 1.5g can definitely be felt as unusual and should be reported for the good of the next crew.

[Loc-out]

Did they walk away from it? If yes, then is was not a bad landing.:O

[rotornut]

I was on an Indian Airlines 737 (100 or 200) out of Bombay that landed at Poona. On landing the damn thing bounced back in the air only to come down firmly to stay on the ground. A/c was almost full. Was this a hard landing?

[fireflybob]

If there is complete silence whilst taxiing from the runway to the stand it's probably a heavy landing!

[rotornut]

Not complete silence because I groaned - it reminded me of when I was learning to fly!

[Pienkie]

Very interested in the definition of a hard landing - seems that Boeing does not define it in terms of G. On the B737 at MTOW the landing limit is 6'/sec and at MLW it increases to 600'/min. Thus hard landing is weight dependant. For FOQA purposes and in terms of G, how do you define a hard landing?

Greetings

[FlightDetent]

I'm interested in the 737, can you elaborate on the numbers? What would it be for our -500s that have MTOW (reduced) 52.999kg LW 49.895kg. I understand that -500 do not need HGW provisioning and thus the very airframe can go as high as 62 tonnes or so. Would there be any diffrence in the limits?

Our FOQA stands at 1.9g as stated above. And it is ugly! :ooh:

Cheers,
FD.

[False Capture]

Avoid heavy/hard landings - fly the BAe 146!:ok:

[UKpaxman]

Errr, you haven't flown the 146 into Scatsta obviously.....landing gear has a fantastic ability to cushion most heavy landings but I've still bounced at least twice before landing properly....if the overhead consoles pop out you know you had a 'spirited' landing.
That said the guys from Flightline do a fantastic job in pretty grim weather conditions.

[False Capture]

landing gear has a fantastic ability to cushion most heavy landings but I've still bounced at least twice before landing properly
I guess you're working on the age-old rules:

1) Any landing you walk away from is a good one.
2) Any landing which allows you to use the plane afterwards is a brilliant one.