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Eurocopter analysis of the EC225 Controlled Ditching on Oct 22nd - 2012

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Eurocopter analysis of the EC225 Controlled Ditching on Oct 22nd - 2012

1. Oct 22 nd event description

2. How similar are the two ditchings from May and Oct ober?

3. Analysis and measures following 1 st event on May 10 th?

4. Findings following 2 nd second event on October 22 nd

5. EC225 Emergency Lubrication System

6. Next Actions

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October 22nd event description

On October 22nd, 2012, during a flight to an offshore platform, a controlled ditching was performed by an EC225 helicopter.

No one on board was injured and everyone was brought back to land safely. The helicopter remained afloat thanks to its emergency floatation gear and was recovered by a ship.

An emergency lubrication warning light came on and resulted in the crew making the decision to perform a controlled ditching, as required by the flight manual.

After visual inspection of the main gearbox, a crack of the bevel gear vertical shaft was noticed close to the welded area. The controlled ditching of the 1st EC225 on May 10th, 2012 was also the result of such failure.

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October 22nd event description

Sequence of events 1/2

1. During cruise flight, “low oil pressure” warning on both main and secondary oil pumps

2. Also MGB (Main Gear Box) Oil Pressure caption and MGB chip caption illuminated.

3. Crew carries out "Total Loss of MGB Oil Pressure checklist"

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360°Crack

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October 22nd event description

Sequence of events 2/2

4. Crew activate “Emergency Lubrication” => Glycol injection lubricating the MGB for 30 minutes of flight.

5. Warning indicates EMLUBmalfunction.

6. Crew follows procedure “land immediately” resulting in controlled ditching.

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How similar are the two ditchingsfrom May and October?

The transmission from the engine power to the main rotor shaft was not interrupted leading to a powered landing on water (Approx. 8 min of powered flight between “low oil pressure” warning and controlled ditching).

Same sequence of events in the cockpit.

360°crack on the bevel gear vertical shaft close to the welded area.

Glycol presence in the MGB, indicating that the Emergency Lubrication System was activated despite EMLUB warning.

Both incidents affect the latest generation bevel gear vertical shaft (nitrided treatment) on EC225 equipped with same FADEC version (v12) and both operated from Aberdeen.

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How similar are the two ditchingsfrom May and October?

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HUMS (Health Monitoring System) detected a similar strong vibration rising trend on a vibration sensor (Mod 45) before the crack :

– Approximately 6H before lubrication loss for May (G-REDW)

– Approximately 4,5H before lubrication loss for October (G-CHCN)

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Analysis and measures following 1st event on May 10th

360°crack on the shaft close to welding area

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Bevel gear crack of the May 10 th event

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Analysis and measures following 1st event on May 10th

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Findings• No incidents have occurred during 4.3 million

FH on previous generation shaft (carburized treatment) on former Super Puma versions.

• Examination of the fractured surface showed the crack initiated at the drilled hole in the weld.

• Out of tolerance inner and outer chamfer,

• Corrosion pits around the inner chamfer underneath the plug which seals the drilled hole.

• Finding associated by EC (based on a technical analysis accepted by EASA when releasing the EASB related to the 1st event) with change of manufacturing process on a batch of identified shafts.

Actions taken• Service Bulletin on June 27, for A/C

operating IMC conditions above water and fitted with shafts in the identified batch:– VHM surveillance every 4FH of 2

parameters for 225 (other intervals for other 332)

• Corrective action implemented on Manufacturing process from S/N 5000:– New dimensional tolerances,

roughness, etc. – New plug

• From EC understanding of the loads and subsequent ground testing, undertaken as part of the investigation, it has been verified that the design of the bevel gear vertical shaft withstand the known stresses with the required margins.

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Findings following 2nd event on October 22nd

• October 22nd shaft was not a part of the batch identified after the May 10th incident.

• Further work to confirm where in the area of the weld the crack initiated.

New conservative EASB:

• No shaft S/N limitation, meaning all nitrided shafts are monitored.

• For flights over water:– With serviceable VHM, reduction of inspection interval

– Others : no flight over water beyond safe forced landing distance from land (see SIN 2520-S-00)

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Actions takenFindings

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EC225 Emergency Lubrication System

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Despite EMLUB warning:

• Presence of Glycol throughout the MGB• No visual evidence of other mechanical

damage inside the MGB

As for the May 10th case, the system seems to have operated.

From the May 10th case, all the components of the Warning System were successfully tested individually and more tests are planned on the complete system.

Ongoing investigation on the reason for alarm and possible rectification action (AAIB Safety Recommendation 2012-034).

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Next Actions

Ongoing investigation: detailed examination under AAIB supervision

• Identification of the possible causes of the second case (crack propagation scheme)

• Identification of any similarities with 1st case

• Adaptation of the current measures if needed

Investigating potential complementary measures « additional safety barriers » • In-service examinations

• Operational changes

Confirmation of the exact root cause• Additional bench and flight tests with instrumented MGB

EMLUB warning :• Instrumented engine bench test week 12th Nov.

• Adapted maintenance for dormant failure detection

• Definition of corrective measure upon confirmation of the technical root cause

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Appendix

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On-going tests

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MGB Bench test

Vibration sensor installation

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On-going tests : stress gauge installation

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Flight manual emergency procedure

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