FAA 

Aviation Safety

EMERGENCY 

AIRWORTHINESS DIRECTIVE

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

DATE: December 20, 2010 

AD #: 2011-01-52 

Background 

This emergency AD is prompted by a locknut working loose on the tailboom aft cluster fitting 

strut. Further investigation revealed that the locknut installed on the expandable bolt did not have the 

proper threads. This condition, if not corrected, could result in the strut and driveshaft separating 

from the helicopter and subsequent loss of control of the helicopter. 

FAA’s Determination 

We are issuing this AD because we evaluated all the relevant information and determined the 

unsafe condition described previously is likely to exist or develop in other helicopters of these same 

type designs. 

AD Requirements 

This AD requires, before further flight, unless accomplished previously, removing the 

locknut, part number MS21043-3. Reinstalling the locknut while determining the locknut drag torque 

is then required. If the drag torque is a minimum of 2 in-lbs, retorquing the locknut to 23 in-lbs is 

required. If the drag torque is not at least 2 in-lbs, replacing the locknut with an airworthy locknut is 

required. 

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. 

Pursuant to this Authority delegated to me by the Administrator, we are hereby issuing this 

Emergency Airworthiness Directive (AD). 

2011-01-52 SCHWEIZER AIRCRAFT CORPORATION: Directorate Identifier 2010-SW-111-

AD. 

Effective Date 

(a) This Emergency AD is effective upon receipt. 

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Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Model 269A, A-1, B, C, C-1, and Th-55 series helicopters, that have an 

Aft Cluster Fitting Modification Kit, part number SA-269K-106, installed; Model 269C helicopters, 

serial numbers 1846 and larger; and Model 269C-1 helicopters, serial numbers 0156 and larger, 

certificated in any category. 

Unsafe Condition 

(d) This AD is prompted by a locknut working loose on the tailboom aft cluster fitting strut. 

Further investigation revealed that the locknut installed on the expandable bolt did not have the 

proper threads. This condition, if not corrected, could result in the strut and driveshaft separating 

from the helicopter and subsequent loss of control of the helicopter. 

Compliance 

(e) Required before further flight, unless accomplished previously, remove the locknut, part 

number MS21043-3. Reinstall the locknut while determining the locknut drag torque. If the drag 

torque is a minimum of 2 in-lbs, retorque the locknut to 23 in-lbs. If the drag torque is not at least 

2 in-lbs, replace the locknut with an airworthy locknut. 

Special Flight Permit 

(f) Special flight permits will not be issued.

Alternative Methods of Compliance (AMOCs) 

(g) The Manager, New York Aircraft Certification Office (NYACO), FAA, has the authority 

to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In 

accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight 

Standards District Office, as appropriate. If sending information directly to the manager of the 

NYACO, send it to the attention of the Continued Operational Safety program manager. 

Note: Before using any approved AMOC, we request that you notify your appropriate 

principal inspector, or lacking a principal inspector, your local Flight Standards District Office. 

Other Information 

(h) For further information about this AD, contact: Stephen Kowalski, Aerospace Engineer, 

Airframe and Propulsion Branch, ANE-171, 1600 Stewart Ave., suite 410, Westbury, New York 

11590, telephone (516) 228-7327, fax (516) 794-5531. 

Subject 

(i) The Joint Aircraft System Component (JASC) Code is 5302: Rotorcraft Tailboom. 

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Issued in Fort Worth, Texas, on December 20, 2010. 

M. Monica Merritt, 

Acting Manager, Rotorcraft Directorate, 

Aircraft Certification Service. 

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