### AW: Clarification Requested on two items associated with Airbus

Petition for Exemption
[Note: This e-mail included two Airbus-proprietary PDF attachments, neither of which is posted to the Federal Register due to the confident ial nature of the material:

• June, 2008 board-meeting document, ref. no. V03MN08 1446

• Distributed Primary Flight Controls Architecture P4 .14d]

from: Koenig, Michael

to: Stephen Happenny

10/15/2010 08:44 AM

Hello Steve,

This is to provide the Airbus answer to the two poi nts you requested clarification for.

(1) Does the A350-900 airplane design include a pai r of spoilers that will have an electrical back-up actuation? Please provide a ref erence number for documentation.

(2) Is it correct that in case of total loss of all hydraulic power in combination with a significant damage of the pressurized fuselage, the aircraft will still be able to deploy a pair of spoilers in order to descend quickly to a s afe altitude?

Answer:

The A350-900 is fitted with a pair of spoiler EBHA (Electrical Back-up Hydraulic Actuator) which in case of a hydraulic system failu re can work as an electrical actuator.
This is documented in the ATA27 Certification Plan (Ref. 00V270P0000/P00).

Note: For the A350, in case of loss of one engine, all the Primary Flight Control Actuators remain available. In this case, both hydr aulic circuits are fed by the two pumps on the remaining engine. This is also documented in ref. 00V270P0000/P00. For illustration please find a [Airbus proprietary] sch ematic of the A350-900 flight controls
architecture attached.

In the context of the FAR 25.841 amdt 87, we follow the certification policy set forth in the FAA Interim Policy on High Altitude Cabin Decom pression, ref. ANM-03-112-16:

Quote In analyzing system and structural damage caused by fragments from an UEF, additional structural damage can be assumed to be limited to t hat engine. Regarding engine powered systems, other than loosing the thrust, engine blee d air, and engine accessory power onthe engine suffering the UEF, the operation of othe r airplane systems can be assumed to

be normal. Therefore, the airplane should be capabl e of performing a V
mo /M
mo emergency decent (i.e., spoilers fully deployed if appropriate, maximum descent rate,

V
mo /M
mo speed). Unquote

The agreement reached between EASA and Airbus cited below:

Quote

• Hydraulic System power is lost from the failed engi ne, but there is no additional damage to the hydraulic lines from the UERF.

• One Green and One Yellow Pump on remaining engine a vailable. Thus all spoilers remain powered and are capable of meeting the emergency descent criteria, analysis will be contained in Exemption D ossier. Unquote

This is documented in the minutes of 2nd TBM which took place 10-11 June 2008, ref. V03MN0814469 (attached) [the referenced document is Airbus proprietary and is therefore not posted in the Federal Docket].

Could you please let me know if this clarifies the issue.

Regards from Indian Summer in Hamburg

Michael König

Michael König Product Integrity - EAAC2 Certification Manager ATA 21, 38 Airbus Operations GmbH Kreetslag 10 D-21129 Hamburg (Germany)
Phone: +49 40 743 80285
Fax: +49 40 743 76489