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FAA

Aviation Safety

EMERGENCY 

AIRWORTHINESS DIRECTIVE

www.faa.gov/aircraft/safety/alerts/

DATE: October 30, 2015

AD #: 2015-22-53

This superseding Emergency Airworthiness Directive (AD) 2015-22-53 is being sent to 

owners and operators of Airbus Helicopters Model AS350B3 helicopters 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 prohibited performing the yaw load 

compensator check (collective switch) during preflight procedures and instead required performing it 

during post-flight procedures. Emergency AD 2015-22-52 also required the yaw servo hydraulic 

switch (collective switch) to be in the “ON” (forward) position before taking-off. The actions in 

Emergency AD 2015-22-52 were 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.

Emergency 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 

investigations, 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 conditions in the events are indicative of takeoffs without hydraulic T/R assistance 

caused by a lack of pressure in the T/R hydraulic system. When taking off without 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 the accidents and incident, the 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 correct an unsafe condition for Airbus Helicopters Model AS 350 B3 

helicopters, equipped 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 in the Rotorcraft Flight 

Manual (RFM). According to EASA, performing the T/R hydraulic preflight checks improperly may 

result in reduced function of the T/R hydraulic system, thereby significantly increasing the T/R 

control load for the pilot. 

Actions Since 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 recording 

compliance.
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FAA’s Determination

This 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 notified us of the unsafe condition described in the EASA AD. We are issuing this 

Emergency 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 type 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 inserting specific pages of the bulletin into 

the RFM. 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 also issued Safety Information Notice No. 2944-S-29, Revision 0, dated 

August 26, 2015 (SIN 2944-S-29), which warns that attempting to take 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 RFM 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, the yaw load compensator 

check has been moved from preflight to post-flight procedures. Further, SIN 2944-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 RFMs.

Emergency AD Requirements

This Emergency 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 This Emergency AD and the EASA AD 

The EASA AD requires revising the RFM 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 RFM changes. This 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 Emergency AD to be an interim action. The design approval holder is 

currently developing a terminating action that will address the unsafe condition identified in this 

Emergency AD. Once this terminating action is developed, approved, and available, we might 

consider additional rulemaking.
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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 Administrator. “Subtitle VII, 

Aviation Programs,” describes in more detail the scope of the Agency’s authority.

We are issuing this 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 for practices, 

methods, and procedures the Administrator finds necessary for safety in air commerce. This 

regulation is within the scope of that authority because it addresses an unsafe condition that is likely 

to exist or develop on products identified in this rulemaking action.

Adoption of the Emergency Airworthiness Directive (AD)

We are issuing this Emergency AD under 49 U.S.C. Sections 106(g), 40113, and 44701 

according to the authority delegated to me by the Administrator.

2015-22-53 Airbus Helicopters: Directorate Identifier 2015-SW-083-AD. Supersedes Emergency 

AD 2015-22-52.

(a) Applicability

This Emergency 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 Emergency AD: The dual hydraulic system for Model 

AS350B3 helicopters is referred to as Airbus modification OP 3082 or OP 3346.

(b) Unsafe Condition

This Emergency 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 Emergency 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 Emergency AD within the 

specified compliance time unless it has already 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: 
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(1) Stop performing the yaw load compensator check (ACCU TST switch) during preflight 

procedures, and instead perform the yaw load compensator check during post-flight procedures after 

rotor shut-down. 

(2) The yaw servo hydraulic switch (collective switch) must be in the “ON” (forward) 

position before takeoff.

Note 2 to paragraph (f)(2) of this Emergency AD: The 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 Permits

Special flight permits are prohibited.

(h) Alternative Methods of Compliance (AMOCs)

(1) The Manager, Safety Management Group, FAA, may approve AMOCs for this 

Emergency AD. Send 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 part 119 operating certificate or under 14 CFR 

part 91, subpart 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 operating any aircraft complying with this Emergency AD through an AMOC.

(i) Additional Information

(1) For further information contact: Stephen Barbini, Flight Test Engineer, Regulations and 

Policy Group, Rotorcraft Directorate, FAA, 10101 Hillwood Pkwy, Fort 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 the 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.
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(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.