EASA med utvidelse av Emergency Airworthiness Directive

Havarier og nødlandinger - Sertifiserende myndigheter i fokus
Etter nødlandingen i sjøen på engelsk side den 22. oktober har EASA utvidet sitt EAD til å gjelde EC225 og alle AS332. En skjelner nå mellom helikoptre som har Vibration Health Monitoring (VHM) og de som ikke har det. Tiden mellom nedlasting av vibrasjonsdata er satt til 3t for EC225 og mellom 4,5 og 6t for andre varianter av typen. Det betyr at EC225 ikke kan settes på de lange turene eller f.eks. ikke kunne shuttle mellom platformer til havs i forbindelse med disse lengre turene. Eurocopter sier at de arbeider med løsninger på akkurat dette EC225 problemet.

Etter den fatale ulykken med en Bond AS332L2 den 1. april 2009 så er det en del som skurrer. Jeg liker spesielt ikke holdningene til Eurocopter i denne sammenheng, bl.a. "4,5 million of hours"..  og etterprøving av flygere som bruker sjekklista. Jeg liker heller ikke at HUMS data ikke har blitt benyttet oftere og hatt et større perspektiv gjeldende for MGB data.


The AAIB invited the Bureau d'Enquêtes et d'Analyses pour la sécurité de l'Aviation Civile (BEA), Eurocopter, the European Aviation Safety Agency (EASA), and the UK Civil Aviation Authority to participate.^[7] The AAIB released a third press statement on 4 April 2009 stating that work to recover the wreckage of G-REDL was continuing.^{[citation needed]}
On 11 April the AAIB released its initial report into the accident in which it stated that the immediate cause of the accident was a "catastrophic failure of the main rotor gearbox" and the consequent detachment of the main rotor. Three safety recommendations were made, the first of which was that all Super Puma helicopters should receive additional checks on the main rotor gearbox epicyclic module.^[16]
On 17 April the AAIB released a second report noting that metallic debris from the gearbox had been detected 34 flying hours prior to the helicopter crash. However, "no signs of an incipient gearbox failure were detected". In response, the EASA ordered an "urgent" inspection of the gearboxes on both the AS332L2 Super Puma and the EC225LP Super Puma. Helicopter operators were given to 24 April to complete the inspections.^[17][18]
On 16 July the AAIB published AAIB Special Bulletin: 5/2009 detailing further progress in the investigation, including two further safety recommendations 2009-74 and 2009-75. These respectively called on the EASA to urgently review the manuals on magnetic particle detection and on planetary gear inspection.^[19]
On 24 November 2011 the AAIB published its Formal Report 20/2011 into the accident. The cause of the accident was attributed to the catastrophic failure of the Main Rotor Gearbox as a result of a fatigue fracture of a second stage planet gear in the epicyclic module.^[20]
In addition the investigation identified three contributory factors:
1. The 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.
2. After 25 March 2009, the existing detection methods did not provide any further indication of the degradation of the second stage planet gear.
3. The ring of magnets installed on the AS332 L2 and EC225 main rotor gearboxes reduced the probability of detecting released debris from the epicyclic module.
Seventeen Safety Recommendations were made as a result of the investigation.

A Eurocopter EC225 operated by Bond Offshore Helicopters with 14 on board ditched safely into the North Sea on May 10. At 12:13 p.m., G-REDW made “a controlled descent 24 nm offshore,” according to Bond. The investigation is focusing on the failures of two main-gearbox lubrication systems–the standard one and the back-up one.
Mai 2012 ditching
The helicopter was en route from Aberdeen to the Ensco102 Maersk Resilient platform. The captain and the copilot followed “standard operating procedures” after the helicopter suffered “a loss of gearbox oil pressure,” Bond said. The aircraft remained afloat and upright thanks to its emergency floats–a major contributor to the absence of fatalities. Bond suspended all EC225 flights.

Main Gearbox Oil Pressure Slips to Zero
According to an AAIB special bulletin released on May 13, the event began, for the crew, when the main-gearbox oil-pressure gauge indicated zero, along with other warnings. The gearbox oil temperature started to increase.
The commander reduced speed to 80 knots, turned back toward the coast and initiated a descent. The crew activated the emergency lubrication system, which is supposed to allow 30 minutes of flight. During the descent, the warning light for this system illuminated. The associated procedure is to land immediately, the AAIB said. The commander briefed the passengers and carried out a controlled ditching.
The AAIB also made public on May 13 its discovery of a “360-degree circumferential crack in the bevel gear vertical shaft in the main gearbox.” The crack appeared in the vicinity of a manufacturing weld, and the shaft failure disabled the drive to both mechanical oil pumps. After the AAIB released its bulletin, Bond extended its flight suspension to the Eurocopter AS332L2 Super Puma, a helicopter in the same series as the EC225.
This lasted until May 15, when Bond announced it would resume all flights within 24 hours. The move followed what Bond termed “a rigorous engineering analysis and safety risk assessment” that included inspection of the entire fleet. Bond engineers conducted “borescope tests” on the bevel gear shaft of each of its EC225s to establish the absence of a crack.
Bond will continue to use the health usage and monitoring system (Hums) on its EC225s and AS332L2s to monitor vibration in the main gearbox. The Hums had recorded increasing vibration a few flight hours before the failure, the AAIB said.
Bond also said it received enough “information and assurances” from Eurocopter to resume flights. On May 14 Eurocopter released a service information notice that was agreed with the EASA, UK CAA, BEA (France’s investigation bureau) and AAIB. Notably, it contained reminders about pre-flight checks and flight manuals. “The EC225 and AS332L/L2 fleets can be safely operated within the standard operational limits,” Eurocopter stated.
In an emergency AD issued on May 18 for some EC225s, the EASA required operators to keep a close eye on the vibration health monitoring system. For those not equipped with the system, the AD restricts overwater flights to day VFR.

Gearbox History
The helicopter manufacturer and Bond have somewhat different views about the gearbox, however. A spokesman for Eurocopter said this is the first time such an accident has happened. He referred to some 4.5 million hours of experience with this design, notably on the AS332. But Bond maintains that the failed gearbox was fitted with a bevel shaft specific to the EC225 and certified in 2004, which implies less experience than the millions of hours Eurocopter cites. In any case, the emergency lubrication system has logged less flight time than the original gearbox design.
In a statement released on May 15, Bond said it continues to work with Eurocopter and the regulatory authorities “to find a permanent solution to the [EC225] issues that have challenged the industry.” The operator added it is “confident there is no link between the gearbox-related accidents that Bond Helicopters has experienced, the causes of which have been proved to be beyond [Bond’s] control.”
The Eurocopter spokesman pointed out that neither the AAIB nor the EASA has required any aircraft grounding. As part of the investigation, Eurocopter is studying the crew’s decision to ditch the EC225 immediately.
The manufacturer is also scrutinizing the maintenance history of the accident gearbox. Investigation of the 2009 fatal crash of a Bond-operated Eurocopter AS332L2 in the North Sea revealed that a particle had been found on the epicyclic module magnetic chip detector 36 flight hours before the accident. The operator’s maintenance technicians did take action, but they did not recognize the presence of the particle as indicating degradation of the planet gear. One of the final investigation report’s highlights was its assertion of imperfections in maintenance programs.
The Helicopter Safety Steering Group (HSSG) met on May 14 “to share preliminary information” about the incident. After the meeting, the HSSG said, “We understand that detailed discussions involving … Eurocopter, the AAIB and CAA have concluded that the particular models in question are fully airworthy. We have had assurances by the helicopter operators that their flight operations remain safe.” Three helicopter operators in the North Sea–Bond, CHC and Bristow–have EC225s in their fleet. The HSSG consists of helicopter operators, oil and gas operators and contractors, offshore trade unions, Balpa, regulators HSE and CAA, and trade association Oil & Gas UK.

Så fulgte CHC ditchingen den 22. oktober
Jeg blir intervjuet av Teknisk Ukeblad og uttaler at "det er tilbake til steinalderen". Med det mener jeg alle de hendelsene som Pumaflåten var utsatt for på åtti- og nittitallet på engelsk og norsk side av Nordsjøen.
Flygerne fikk varsel om tap av oljetrykk til MGB. Nødsmøresystemet ble aktivert, men det indikerte at det hadde feilet. Det viste seg at da en drenerte MGB på tørt land, så inneholdt den en stor del av glycol som er en del av nødsystemet. Flygerne fikk altså et galt varsel. Men også her var det en sprekk i kassen der de to drevene til oljepumpene er festet. Disse drevene var ikke omfattet av den AD som ble utgitt i den forrige hendelsen. Også her viste HUMS data vibrasjoner som gikk ut over fastsatte grenser på de to flyvningene forut for denne. Data var ikke påkrevet å laste ned siden de ikke var blant den lot`en med akslinger som nevnte AD omhandlet.

Jeg er veldig skuffet over både Eurocopter og AAIB som ikke har gått dypere inn i materien når det gjaldt sveisesømmer utført under byggingen av gearboksene. Eurocopter har altså valgt en annen løsning enn "dry run" i 30 minutter. De sprøyter glycol inn i boksen for å føre bort varme. Spørsmålet om design av pumpesystemet er verdig en grundig gjennomgang. Også dette helikopteret er sertifisert av Luftfartstilsynet uten å ha redundans i pumpesystemet. Det er grunn til å spørre seg om både S-92A og EC225 bør diskvalifieres fra konkurransen som Sea Kingen etterfølger.

Du må merke deg at nødlandinger i sjøen er forbundet med mange ukjente faktorer, særlig når det er mørkt og når det blåser mye. Feilvarsler som tvinger helikopteret ned kan føre til en katastrofe.....

EHST - European Helicopter Safety Team må jo bekymre seg noe veldig.