Airworthiness Directive · Amendment 39-18494 · Rotorcraft servo system
Bell Helicopter Textron Canada Helicopters
This AD applies to Bell Helicopter Textron Canada (Bell) Model 222, 222B, 222U, 230, and 430 helicopters, with a main rotor hydraulic servo actuator (servo actuator) part number (P/N) 222-382-001-107 installed, certificated in any category.
We are superseding Airworthiness Directive (AD) 2010-19-51 for Bell Helicopter Textron Canada (Bell) Model 222, 222B, 222U, 230, and 430 helicopters. AD 2010-19-51 required inspecting parts of the main rotor hydraulic servo actuator (servo actuator) for certain conditions and replacing any unairworthy parts before further flight. This new AD requires installing a servo actuator with a new stainless steel piston rod. This AD was prompted by a collective servo actuator malfunction. We are issuing this AD to detect corrosion on a piston rod, which could result in failure of the servo actuator and consequent loss of helicopter control.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
Before further flight:
(1) Disassemble each servo actuator to gain access to the piston rod as shown in Figures 1 through 5 and by following the Accomplishment Instructions, paragraph 3.A., Part I., of Woodward HRT Alert Service Bulletin No. 141600-67-02, dated August 18, 2010 (Woodward ASB).
(2) Clean the entire piston rod and nut using acetone and a nylon bristle brush removing all contaminates to allow for inspection. Inspect the grind relief configuration for the piston rod and nut as shown in Figure 6 of the Woodward ASB. If the grind relief is unacceptable as shown in Figure 6, replace the piston rod and the nut with airworthy parts.
(3) Using a 10X or higher magnifying glass, visually inspect the nut for any corrosion or any damage to the threads. If you find any corrosion or any damage to the threads, replace the nut with an airworthy nut.
(4) Using a 10X or higher magnifying glass, visually inspect the piston rod as shown in Figure 7 of the Woodward ASB for any corrosion, visible lack of cadmium plate (gold or gray color), or damage to the piston rod. For the purposes of this AD, damage to the piston rod is defined as pitting, a visible scratch, a crack, or a visible abrasion.
(i) If there is any corrosion or visible lack of cadmium plate or any damage to the piston rod in the Critical Areas as shown in Figure 7 of the Woodward ASB, replace the servo actuator with servo actuator P/N 222-382-001-111 or P/N 222-382-001-111FM before further flight.
(ii) If there is any corrosion or visible lack of cadmium plate on the piston rod in areas that are not considered Critical Areas as shown in Figure 7 of the Woodward ASB, rework the piston rod by removing any surface corrosion that has not penetrated into the base material by lightly buffing. Clean the part using acetone and a nylon bristle brush to remove any residue. Comply with paragraphs (f)(5) through (f)(6) of this AD. Within 1,200 hours time-in-service (TIS) or 1 year, whichever occurs first, replace the servo actuator with servo actuator P/N 222-382-001-111 or P/N 222-382-001-111FM.
(iii) If there is any corrosion that is red or orange in color, magnetic particle inspect the piston rod for a crack.
(A) If there is a crack, replace the servo actuator with servo actuator, P/N 222-382-001-111 or P/N 222-382-001-111FM before further flight.
(B) If there is no crack, comply with paragraphs (f)(5) through (f)(6) of this AD. Within 2,400 hours TIS or 2 years, whichever occurs first, replace the servo actuator with servo actuator P/N 222-382-001-111 or P/N 222-382-001-111FM.
(iv) If there is no corrosion, visible lack of cadmium plate, or damage to the piston rod, comply with paragraphs (f)(5) through (f)(6) of this AD. Within 3,000 hours TIS or 4 years, whichever occurs first, replace the servo actuator with servo actuator P/N 222-382-001-111 or P/N 222-382-001-111FM.
(5) Inspect the portion of the piston rod for any absence of cadmium plating (bare base metal), as shown in Figure 7 of the Woodward ASB. If there is any bare base metal on the piston rod in this area, apply brush cadmium plating to all bare and reworked areas using SPS5070 or equivalent 0.0002 to 0.0005 inch thick and rework the piston rod by following the Accomplishment Instructions, paragraph C., Part III, C.1.1.1. through C.1.1.3., of the Woodward ASB.
(6) Reassemble the servo actuator by following the Accomplishment Instructions, paragraph C, Part III, 1.1.4. through 3.3.4. of the Woodward ASB.
Compliance with the Woodward ASB or with AD 2010-19-51 (75 FR 71540, November 24, 2010) before the effective date of this AD is considered acceptable for compliance with the corresponding inspections specified in paragraph (f) of this AD. If you replaced the piston rod pursuant to the Woodward ASB or paragraph (d)(1) or (d)(3) of AD 2010-19-51, apply the requirements of paragraph (f)(4)(iv) of this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
