Hard Landing Parameters, Aircarrier Aircrafts
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Hard Landing Parameters, Air Carrier Aircrafts
I´d be interested to have an idea of the parameters as far as G´s and descend rate at touch dawn that would bring it into a Hard Landing inspection.
Guess those aircrafts also have different levels of inspections depending on the severity of the parameters.
Brgds,
Manuel
Guess those aircrafts also have different levels of inspections depending on the severity of the parameters.
Brgds,
Manuel
Last edited by manuel ortiz; 11th Feb 2010 at 02:18.
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I too would be interested in whether a "hard" landing instigates any special inspections. By hard landing I mean those hard enough to prompt an apology from the flight deck.
Some years ago I experienced two such landings in the same airframe within two days. Both captains apologised for the bad landing, (different crews, BTW). It made me wonder whether the flight crew reported the fact of the landings to engineering. Also it occurred to me that as it was the same aircraft, whether there was a problem with it and each time it had caught out the PIC. If these things were not reported, this aircraft could have gone on having hard landings until something broke.
I suppose it depends on what is technically a "hard" landing.
Some years ago I experienced two such landings in the same airframe within two days. Both captains apologised for the bad landing, (different crews, BTW). It made me wonder whether the flight crew reported the fact of the landings to engineering. Also it occurred to me that as it was the same aircraft, whether there was a problem with it and each time it had caught out the PIC. If these things were not reported, this aircraft could have gone on having hard landings until something broke.
I suppose it depends on what is technically a "hard" landing.
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On todays high tech airliners it itself will auto generate a hard landing report in printout to the cockpit and an electronic report to maintenance will also be included.
G´s and descend rate parameters will be provided. Required level of inspections will to a great extend depend on this.
G´s and descend rate parameters will be provided. Required level of inspections will to a great extend depend on this.
G/VS...
Hi.
I have generally used the VS at 1 sec before touchdown for the most reliable assessment of a hard landing.
The g recorded by the QAR/AIMS can give distorted information, as it may be affected by pitch rate & cg location. The gz accelerometer is normally located at a natural node of the longitudinal axis, and is not often near the average cg location.
Algorithms to filter pitch rate out of the vertical load are not that great...
The sink rate immediately before touchdown has few confounding factors, and normally a value around 550FPM at TD-1sec will result in about 1.7g.
good luck with it, the manufacturers normally don't recommend the use of the QAR data to assess a hard landing, it is more often the case that the pilots opinion is the determinant.
FDR
I have generally used the VS at 1 sec before touchdown for the most reliable assessment of a hard landing.
The g recorded by the QAR/AIMS can give distorted information, as it may be affected by pitch rate & cg location. The gz accelerometer is normally located at a natural node of the longitudinal axis, and is not often near the average cg location.
Algorithms to filter pitch rate out of the vertical load are not that great...
The sink rate immediately before touchdown has few confounding factors, and normally a value around 550FPM at TD-1sec will result in about 1.7g.
good luck with it, the manufacturers normally don't recommend the use of the QAR data to assess a hard landing, it is more often the case that the pilots opinion is the determinant.
FDR
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For us a hard landing inspection is required typically if the touchdown rate is greater than 8 - 10 feet/sec. Being an experimental organisation -that's an equivalent parameter equal to 8 - 10 feet/sec pure vertical - not what you'd be looking at on the VSI. Once while doing some runway performance testing we came in at 12 feet/sec - teeth rattling!
The other thing to bear in mind is how close to MLW the aircraft is at TD - the greater the weight, the more inclined I'd be to have a structural inspection carried out.
The other thing to bear in mind is how close to MLW the aircraft is at TD - the greater the weight, the more inclined I'd be to have a structural inspection carried out.
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?I I read the original question properly? I think carrier aircraft are built for 16fps as 'standard', but where the 'heavy landing' bit comes in, I don't know - pilot's teeth broken, maybe?
I was 'amused' by Dawdler's idea of 'the Captain' apologising for the bad landing
I was 'amused' by Dawdler's idea of 'the Captain' apologising for the bad landing
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See the CAA's FODCOM 2009/21
and, more recently, their AIRCOM 2010/01 for a more or less relevant regulatory view on the subject. Both refer to the same A320 incident in 2009.
and, more recently, their AIRCOM 2010/01 for a more or less relevant regulatory view on the subject. Both refer to the same A320 incident in 2009.
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Generally, non-fighter/attack military aircraft are designed to withstand a vertical acceleration of 4G at design gross weight. For carrier landing, the specialized landing gear design attenuates the magnitude of actual impact so that higher values result in the airframe sustaining impact up to that limit. A strong driver for carrier landing impact requirements is deck heave. Without it, the impact rate of descent can be geometrically derived from the values of aircraft speed relative to ground/deck and approach angle.
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Most CV approaches are flown at 4 or 4.5 deg. Pilot has to have visual of deck and waterline so approach speeds have to be carefully managed. Data on deck heave limits etc are in USN publications.
