Crash super Puma de Bond

alain57 a écrit:suite de la catastrophe du puma en mer du nord le mercredi 01-04 ....16 victimes

http://www.flightglobal.com/articles/2009/04/10/325055/crashed-super-pumas-gearbox-suffered-catastrophic-failure-inquiry.html

rupture boite de transmission principale, aucune chance pour les passagers et l'équipage.....une pensée pour ces malheureux.....

DATE:11/04/09. SOURCE:Flight InternationalEASA orders emergency gearbox checks after Super Puma crash
By David Kaminski-Morrow

European safety authorities have ordered immediate checks on Eurocopter Super Puma gearboxes after initial findings into the fatal North Sea crash on 1 April indicated a serious gearing failure brought the helicopter down.
The emergency directive from the European Aviation Safety Agency (EASA) covers both the AS332L2 - the type lost in the crash - as well as EC225LP variants of the Super Puma.

Preliminary findings of the inquiry, says EASA, suggest the accident is "connected with a degradation" of the epicyclic module of the main gearbox.

"In the light of this information the detection of any contamination of the main gearbox is of utmost importance as a precautionary measure," it adds.

Operators of AS332L2s need to check the magnetic plug of the main gearbox's epicyclic reduction gear module daily, and ensure that correct maintenance has been applied in case of the discovery of any particle on the plug.

If particles were detected during the previous 200 flight hours without a complete maintenance check, it says, the epicyclic module must be disassembled and inspected.

Companies operating the EC225LP must disassemble and inspect this module each time particles are detected on the magnetic plug, and comply with a similar 200-hour historical check.

The directive is effective immediately.

All 16 personnel on board the crashed Super Puma were killed after the gearbox failure which was followed by detachment of the rotor head and main rotor blades.

Eurocopter has issued an alert service bulletin to all AS332L2 operators following the release of the initial Air Accidents Investigation Branch report into the accident.

The manufacturer describes the measure as "precautionary"....

....and adds: "We are committed to working closely with the regulatory authorities, investigators, and operators and customers to implement any required operational and maintenance procedures.

"At Eurocopter, safety is and has always been the number one priority."

It says that 83 AS332L2 helicopters are in service with 20 operators around the world, and have collectively accumulated over 3 million flight hours.

alain57 a écrit:Bonjour Sevrien, vérification journalière de la présence de copeaux ou de particules métallique, ils prennent pas de risques, normal après un tel drame.....
désolidarisation du rotor principal, il a du y avoir un grippage rapide ou une rupture de pignon suivie du blocage instantané de la gearbox.....
pas de chance pour les pauvres malheureux a bord....

sevrien a écrit:Bonjour, Alain !

alain57 a écrit:Bonjour Sevrien, vérification journalière de la présence de copeaux ou de particules métallique, ils prennent pas de risques, normal après un tel drame.....
désolidarisation du rotor principal, il a du y avoir un grippage rapide ou une rupture de pignon suivie du blocage instantané de la gearbox.....
pas de chance pour les pauvres malheureux a bord....

Et merci pour ces analyses de professionnel, des possibilités / probabilités qui nous permettent de voir plus clair !
Oui, ... hélas, ... dans de tels accidents, les chances pour les pilotes et les passagers sont plus que minces !

Investigators examining the wreckage of the Bond Offshore Eurocopter Super Puma AS332L2 that crashed off north-east Scotland in the UK on 1 April have issued an additional urgent inspection requirement for all operators of the type, including the EC225LP variant.

The UK Air Accidents Investigation Branch has now issued the following information: "The investigation has determined that a failure within the epicyclic reduction gearbox module of the main rotor gearbox resulted in the rupture of the gearbox case, which allowed the main rotor head to separate from the helicopter.

Examination of the remains of the epicyclic gearbox, and associated areas of the helicopter, continues apace with the aim of establishing as soon as possible the sequence of the failure and initiating cause."

The associated recommendation reads: "It is recommended that Eurocopter (Si, si ! Eurocopter ! ) with the European Aviation Safety Agency, develop and implement an inspection of the internal components of the main rotor gearbox epicyclic module for all AS332L2 and EC225LP helicopters as a matter of urgency to ensure the continued airworthiness of the main rotor gearbox.

This inspection is in addition to that specified in EASA emergency airworthiness directive 2009-0087-E, and should be made mandatory with immediate effect by an additional EASA emergency airworthiness directive."

The Air Accidents Investigation Branch had already issued an inspection regime that required frequent checks of the aircraft's gearbox metallic chip detectors and magnetic plugs, but it now says: "This procedure was in effect being carried out on the helicopter involved in the accident. This resulted from the discovery of a small chip of metallic debris on the epicyclic gearbox module chip detector some 34 flying hours before the failure.

"However, during the period between the discovery of the chip and the accident, no signs of an incipient gearbox failure were detected."

The AAIB says it was issuing the instruction for detailed checks on the epicyclic gearbox components because "the cause of the failure has yet to be identified, and the failure occurred without apparent warning to maintenance or flightcrews".

he final report into the catastrophic accident involving a Bond Helicopters Eurocopter AS332L2 Super Puma over the North Sea two years ago has confirmed that a sudden main gearbox failure caused the main rotor to separate from the airframe at 2,000ft (610m), resulting in an unsurvivable descent into the sea.

The UK Air Accident Investigation Branch's report on the 1 April 2009 accident, which resulted in the death of all 16 people on board, described the primary cause: "The catastrophic failure of the main rotor gearbox was a result of a fatigue fracture of a second stage planet gear in the epicyclic module."

The AAIB said that indications in the flight data recorder of metal chips accumulating in the oil occurred 3min before the gear failure, but the first indication the crew had of problems was a sudden dramatic fall in the main gearbox oil pressure just 20s before the main rotor separated from the airframe. The report says that "neither the weather nor the crew's actions were factors in the accident".

The report says: "Actions taken following the discovery of a magnetic particle on the epicyclic module chip detector on 25 March 2009, 36 flying hours prior to the accident, resulted in the particle not being recognised as an indication of degradation of the second stage planet gear which subsequently failed. After 25 March the existing detection methods did not provide any further indication of further degradation of the second stage planet gear."

Referring to a particular aspect of the design of the chip detection systems in the engine, the AAIB stated: "The ring of magnets installed on the AS332L2 and EC225 main rotor gearboxes reduced the probability of detecting released debris from the epicyclic module." It said no manufacturing defects were discovered in any of the components.

There were epicyclic chip indications recorded in the aircraft's health and usage monitoring system (HUMS) that could have been an advance indicator of gear wear, the report observes, but they were not picked up by the HUMS ground analysis system because the HUMS data card had not been closed down correctly. The AAIB has recommended that procedures for ensuring card closure be reviewed.

The investigation also noted that a possible opportunity for the manufacturer to have recognised an abnormal degradation in the gearbox was missed as a result of a communications misunderstanding between Eurocopter and Bond, which led Eurocopter to believe that Bond was reporting magnetic chip results following inspection of the ring of magnets on the oil separator plates in the epicyclic module, but the operator had not done that.

The AAIB has made 17 recommendations, most of which call for additional maintenance procedures or future research that might make the detection of such an impending failure more likely.