1 F AA Aviation Safety 

## EMERGENCY AIRWORTHINESS DIRECTIVE
www.faa.gov/aircraft/safety/alerts/

DATE: October 30, 2015 AD #: 2015

- 22

- 53

This superseding E mergency A irworthiness D irective ( AD ) 2015

- 22

- 53 is being sent to owners and operators of Airbus Helicopters Model AS350B3 helicopter s to correct an error in terminology and a defect in recording compliance in Emergency AD 2015

- 22

- 52

. Background
On October 28, 2015 we issued Emergency AD 2015

- 22

- 52 for Airbus Helicopters Model AS350B3 helicopters with a dual hydraulic system that prohibit ed performing the yaw load compensator check (collective switch) during preflight procedures and instead require d performing it during post

- flight procedures. E mergency AD 2015

- 22

- 52 also require d the yaw servo hydraul ic switch (collective switch) to be in the “ON” (forward) position before taking

- off. The actions in Emergency AD 2015

- 22

- 52 we re intended to prevent takeoff without hydraulic pressure in the T/R hydraulic system, loss of T/R flight control, and subsequent loss of control of the helicopter.

E mergency AD 2015

- 22

- 52 was prompted by two accidents and one incident of Airbus Helicopters Model AS350B3 helicopters with a dual hydraulic system installed

. From preliminary investigation s , loss of tail rotor (T/R) control during take

- off was evident in each event

. Each event experienced a counterclockwise rotational yaw immediately after takeoff. It was also noted that the anti

- torque pedals felt jammed or locked in the neutral position by the pilots in the two non

- fatal events. The condition s in the events are indicative of t ak e off s with out hydraulic T/R assistance caused by a lack of pressure in the T/R hydraulic system. When t aking off with out T/R hydraulic assistance with the switch on the collective grip in the “OFF” (aft) position, the yaw load compensator remains discharged and degrades the T/R hydraulic system , which significantly increases the pilot T/R control load and prevents sufficient T/R thrust for takeoff

. Based on th e accidents and incident , t he European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Union, issued EASA AD No. 2015

- 0178 , dated August 26, 2015 , to cor rect an unsafe condition for Airbus Helicopters Model AS 350 B3 helicopters, equ ipped with a dual hydraulic system identified as modification OP 3082 or OP 3346

. EASA advises of a perceived loss of T/R control that mimics jamming during take

- off if the T/R hydraulic preflight checks are not performed in accordance with the checklist i n the Rotorcraft Flight Manual (RFM)

. According to EASA, p erforming the T/R hydraulic preflight checks improperly may result in reduced function of the T/R hydraulic system , thereby significantly increas ing the T/R control load for the pilot.
Actions Sinc e Emergency AD 2015

- 22

- 52 was Issued

After we issued Emergency AD 2015

- 22

- 52 , we received comments noting an error in terminology and a defect in reporting compliance that resulted in confusion in how to comply with the Emergency AD . Therefore, we are superseding Emergency AD 2015

- 22

- 52 to clarify the requirements. Specifically, we referred to the collective switch for the yaw load compensator check, when we should have referred to the ACCU TST switch. We also omitted a method of rec ording compliance.2 FAA’s Determination

Th is helicopter has been approved by the aviation authority of France and is approved for operation in the United States. Pursuant to our bilateral agreement with France , EASA, its technical representative, has notif ied us of the unsafe condition described in the EASA AD. We are issuing this E mergency AD because we evaluated all information provided by EASA and determined the unsafe condition exists and is likely to exist or develop on other helicopters of the same ty pe design.

Related Service Information
Airbus Helicopters issued Service Bulletin No. AS350

- 67.00.66, Revision 1, dated October 22 , 2015 (SB AS350

- 67.00.66 ) , which specifies in serting specific pages of the bulletin into the R FM . These pages revise the preflight and post

- flight hydraulic checks by moving the T/R yaw load compensator check from preflight to post

- flight

. These pages also revise terminology within the flight manuals for the different engine configurations.
Airbus Helicopters al so issued Safety Information Notice No. 2944

- S

- 29, Revision 0, dated August 26, 2015 (SIN 2944

- S

- 29 ), which warns that attempting to tak e off without T/R hydraulic assistance ( which may be caused by the yaw servo hydraulic switch on the collective grip in the “OFF” (aft) position) might be incorrectly perceived as T/R control failure (jam), which could lead to loss of control of the helicopter if not quickly identified and corrected. SIN 2944

- S

- 29 also advises of the R FM update that revises the run

- up hydraulic check starting procedures to no longer specify

“ pressing ” the yaw servo hydraulic switch. To mitigate this potential error, t he yaw load compensator check has been moved from preflight to post

- flight procedures

. Further, SIN 29 44

- S

- 29 states the yaw servo hydraulic switch , which is located on the collective grip , is also called the hydraulic pressure switch or hydraulic cut off switch in various R FMs

. E mergency AD Requirements

This E mergency AD requires , before further flight , revising the rotorcraft flight manual to stop performing the yaw load compensator check ( ACCU TST switch) during preflight procedures and instead performing the yaw load compensator check during post

- flight procedures after rotor shut

- down . This Emergency AD also requires the yaw servo hydraulic switch (collective switch) to be in the “ON ” (forward) position before taking off. The yaw servo hydraulic switch may also be called the hydraulic pressure switch or hydraulic cut off switch.

Differences Between Th is Emergency AD and the EASA AD The EASA AD requires revising the R FM by incorporating procedures contained in Airbus Helicopters Service Bulletin No. AS350

- 67.00.66, Revision 0, dated August 26, 2015 , and informing all flight crew of the R FM change s

. T h is Emergency AD requires revising the RFM by inserting a copy of this Emergency AD or by making pen and ink changes

. Interim Action

We consider this E mergency AD to be an interim action. The design approval holder is currently developing a t erminating action that will address the unsafe condition identified in this E mergency AD. Once this t erminating action is developed, approved, and available, we might consider additional rulemaking.3 Authority for this Rulemaking

Title 49 of the United States Code specifies the FAA’s authority to issue rules on aviation safety. Subtitle I, Section 106, describes the authority of the FAA Ad ministrator. “ Subtitle VII, Aviation Programs, ” describes in more detail the scope of the Agency’s authority.
We are issuing th is rulemaking under the authority described in “ Subtitle VII, Part A, Subpart III, Section 44701, General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations fo r practices, methods, and procedures the Ad ministrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it ad dresses an unsafe condition that is likely to exist or develop on products identified in t his rulemaking action.

Ad option of the E mergency A irworthiness D irective ( AD ) We are issuing this E mergency AD under 49 U.S.C. Section s 106(g), 40113, and 44701 according to the authority delegated to me by the Ad ministrator.

2015

- 22

- 53 Airbus Helicopters : D irectorate Identifier 20 15

- SW

- 0 83

- AD

. Supersedes Emergency AD 2015

- 22

- 52. ( a ) Applicability

This E mergency AD applies to Airbus Helicopters Model AS350B3 helicopters with a dual hydraulic system installed , certificated in any category. Note 1 to paragraph (a) of this E mergency AD: The dual hydraulic system for Model AS350B3 helicopter s is referred to as Airbus modification OP 3082 or OP 3346. ( b ) Unsafe Condition

This E mergency AD defines the unsafe condition as lack of hydraulic pressure in a tail rotor ( T/R ) hydraulic system. This condition could result in loss of T/R flight control and subsequent loss of control of the helicopter. (c) Effective Date

This E mergency AD is effective upon receipt. (d) Affected ADs This Emergency AD supersedes Emergency AD 2015

- 22

- 52 issued on October 28, 2015. ( e ) Compliance You are responsible for performing each action required by this E mergency AD within the specified compliance time unless it has alr ead y been accomplished prior to that time. ( f

) Required Actions Before further flight , insert a copy of this Emergency AD into the rotorcraft flight manual, Section 4 Normal Operating Procedures, or make pen and ink changes to the preflight and post

- flight procedures as follows:4 (1) S top performing the yaw load compensator check ( ACCU TST switch) during preflight procedures, and instead perform the yaw load compensator check during post

- flight proced ures after rotor shut

- down

. (2) The yaw servo hydraulic switch (collective switch) m ust be in the “ON” (forward) position before takeoff.

Note 2 to paragraph ( f ) (2) of this Emergency AD: T he yaw servo hydraulic switch is also called the hydraulic pressure switch or hydraulic cut off switch in various Airbus Helicopters rotorcraft flight manuals.
( g ) Special Flight Permit s
S pecial flight permit s are prohibited. ( h ) Alternative Methods of Compliance (AMOCs)
(1) The Manager, Safety Management Group , FAA, m a y approve AMOCs for this E mergency AD

. S end your proposal to: Stephen Barbini, Flight Test Engineer, Regulations and Policy Group, Rotorcraft Directorate, FAA, 10101 Hillwood Pkwy, Fort Worth, TX 76177; telephone (817) 222

- 5110; email 9

- ASW

- FTW

- AMOC

- Requests@faa.gov.
( 2 ) For operations conducted under a 14 CFR p art 1 19 operating certificate or under 14 CFR p art 91, s ubpart K, we suggest that you notify your principal inspector, or lacking a principal inspector, the manager of the local flight standards district office or certificate holding district office, before ope rating any aircraft complying with this E mergency AD through an AMOC. ( i ) Ad ditional Information (1) For further information contact: Stephen Barbini, Flight Test Engineer, Regulations and Policy Group, Rotorcraft Directorate, FAA, 10101 Hillwood Pkwy, For t Worth, TX 76177; telephone (817) 222

- 5110; email stephen.barbini@faa.gov.
(2) Airbus Helicopters Service Bulletin No. AS350

- 67.00.66, Revision 1, dated October 22 , 2015, and Airbus Helicopters Safety Information Notice No. 2944

- S

- 29, Revision 0, dated August 26, 2015, provide additional information about this Emergency AD. For a copy of th e service information referenced in this Emergency AD, contact: Airbus Helicopters, 2701 N. Forum Drive, Grand Prairie, TX 75052; telephone (972) 641

- 0000 or (800) 232

- 0323; fax (972) 641

- 3775; or at http://www.airbushelicopters.com/techpub

. (3) The subject of this AD is addressed in European Aviation Safety Agency AD No. 2015

- 0178 , dated August 26, 2015

.5 ( j ) Subject Joint Aircraft Service Component (JASC) Code: 2910, Main Hydraulic System.

Issued in Fort Worth, Texas , on October 30, 2015.
Lance T. Gant,
Manager, Rotorcraft Directorate, Aircraft Certification Service.