### FAA Aviation Safety



### DATE: October28, 2015 AD #: 

### 2015-22-52 

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

This Emergency Airworthiness Directive (AD) 2015-22-52 is being sentto owners and operators ofAirbus Helicopters Model AS350B3 helicopters. 

### Background This Emergency ADwas prompted by two acci Helicopters Model AS350B3 helicopters with a dual hydraulic investigations, loss oftail rotor (T/R) control during experienced a counterclockwise rotational yaw · anti-torque pedals feltjammed or events. The conditions in the control caused by a lack ofpressure T/Rhydraulic assistance with the switch on the yaw load compensatorremains discharged and which significantly increases the pilot TIRcontrol load andprevents

. This Emergency AD prohibits performing the yaw load compensator switch) during preflight procedures and instead requires performing it procedures. This emergency AD also requires the yaw servo hydraulic switch switch) to be in the "ON" (forward) position before taking-off. The actions inthis Emergency AD are intended to preventtakeoffwithout hydraulic pressure in the T/R hydraulic system, loss ofTIRflight control, and subsequent loss ofcontrol ofthe helicopter. Based onthe accidents and incident, the European Aviation SafetyAgency (EASA), which is the Technical Agent for the Member States ofthe 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 ofa perceived loss ofTIR control that mimicsjamming during take-offifthe T/R hydraulic preflight checks are not performed in accordance with the checklist in the Rotorcraft Flight Manual (RFM). Accordingto EASA, performingthe T/Rhydraulic preflight checks improperly may result in reduced function ofthe TIRhydraulic system, thereby significantly increasingthe T/R control load for the pilot. 

### FAA'sDetermination This helicopterhas been approved bythe aviation authority ofFrance and is approved fot operation in the United States. Pursuantto ourbilateral agreement with France, EASA, its technical representative, has notified us ofthe unsafe condition described in the EASA AD. We are issuingthis emergency AD because we evaluated all information provided by EASA and determined the unsafe condition exists and is likely to exist ordevelop on otherhelicopters ofthe same type design. 

### Related ServiceInformation 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 ofthe bulletin into the RFM. 1These pages revisethe preflight and post-flighthydraulic checks by movingthe T/R yaw load compensatorcheckfrom preflightto 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 warnsthat attempting to take offwithoutT/Rhydraulic assistance (the yaw servo hydraulic switch on the collective grip in the "OFF" (aft) position) might be incorrectly perceived as T/Rcontrol failure (jam), which could lead to loss ofcontrol ofthe helicopter ifnot quickly identified and corrected. SIN 2944-S-29 also advises ofthe RFM update that revises the run-up hydraulic check starting proceduresto no longer specify the yaw servo hydraulic switch. Pressingthe yaw servo hydraulic switch, which is part load compensator check, dischargesthe yaw load compensator. The yaw load moved from preflightto post-flightprocedures. Further, SIN**L'JLJ·LJ.-~•-L.~** which is located on the collective grip, is also called offswitch in various RFMs.

yaw servo switch. performingthe yaw load and insteadperformingthe yaw This EmergencyAD also requires the yaw be in the "ON" (forward) position beforetaking off. The be calledthe hydraulic pressure switch orhydraulic cut off



### Differences Between This EmergencyAD and theEASAAD The EASA AD requires revisingthe RFM by incorporating procedures contained in Airbus Helicopters Service BulletinNo. AS350-67.00.66, Revision 0, dated August 26, 2015, and informing all flight crew ofthe RFM changes. This EmergencyAD prohibits performingthe yaw load compensator check during preflight procedures and requires it to be performed during post-flight procedures. This Emergency AD also requires the yaw servo hydraulic switch (collective switch) to be in the "ON" (forward) position before taking off. 

### Interim Action We considerthis Emergency AD to be an interim action. The design approval holder is currently developing a terminating action that will addressthe unsafe condition identified in this Emergency AD. Oncethis terminating action is developed, approved, and available, we might consider additional rulemaking. 

### Authority for this Rulemaking Title 49 ofthe United States Code specifiesthe FAA's authority to issuerules on aviation safety. Subtitle I, Section 106, describes the authority oftheFAA Administrator. "Subtitle VII, Aviation Programs," describes in more detail the scope oftheAgency's authority. We are issuing this rulemaking underthe authority described in "Subtitle VII, PartA, Subpart III, Section 44701, General requirements." Underthat section, Congress charges the FAA with promoting safe flight ofcivil aircraft in air commerce byprescribing regulations for practices, methods, and procedures theAdministrator finds necessary for safety in air commerce. This

2

### regulation is within the scope ofthat authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action. Adoption ofthe 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. 2015-22-52 Airbus Helicopters: Directorate Identifier 2015-SW-074-AD. (a) Applicability This Emergency AD applies to Airbus Helicopters Model AS350B3 hel"""''"i-"'""" with a dual hydraulic system installed, certificated in any category. Note 1

### to paragraph (a) ofthis Emergency AD: AS350B3 helicopters is referred to as Airbus

...v ••.uu• 

### (b) Unsafe Condition

(d) Compliance pressure in a tail rotor control and subsequent loss

You are responsible for performing each action required by this Emergency AD within the specified compliance time unless it has already been accomplished priorto that time. (e) Required Actions Before further flight, stop performing the yaw load compensator check (collective switch) during preflightprocedures, and insteadperform the yaw load compensator check during post-flight procedures. The yaw servo hydraulic switch (collective switch) must be in the "ON" (forward) position beforetakeoff. Note 2 to paragraph (e) ofthisEmergency AD: The yaw servo hydraulic switch is also called the hydraulic pressure switch or hydraulic cut offswitch in various Airbus Helicopters flight manuals. 

### (f) Special FlightPermit A special flight permit is prohibited. (g) 

### Alternative Methods ofCompliance (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. 3

### (2) For operations conducted under a 14 CFR part 119 operating certificate or under 14 CFR part 91, subpart K, we suggestthat you notify your principal inspector, or lacking a principal inspector, the manager ofthe local flight standards district office or certificate holding district office, before operating any aircraft complying with this Emergency ADthrough an AMOC. 

### (h) Additional Information (1) 

### For further information contact: Stephen Barbini, FlightTest 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 BulletinNo. AS350-67.00. 2015, and Airbus Helicopters Safety Information Notice N 26, 2015, provide additional information about this information referenced in this AD, contact: TX 75052; telephone (972) 641-0000 http://www ·

Issued in Fort Worth, Texas, on October 28, 2015. LanceT. Gant, Manager, Rotorcraft Directorate, Aircraft Certification Service.

4 

### October 22, dated August

service Grand Prairie,