Airworthiness Directive · Amendment 39-18472 · Main rotor
Airbus Helicopters (formerly Eurocopter France)
This AD applies to Model SA341G and SA342J helicopters with a main rotor head torsion bar (torsion bar) part number 704A33633274 installed, certificated in any category.
We are adopting a new airworthiness directive (AD) for Airbus Helicopters Model SA341G and SA342J helicopters. This AD requires repetitive inspections of a certain part-numbered main rotor hub torsion bar (torsion bar). This AD was prompted by several cases of corrosion in the metal strands of the torsion bar. The actions of this AD are intended to detect corrosion and prevent failure of the torsion bar, loss of a main rotor blade, and subsequent loss of control of the helicopter.
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.
(1) For each torsion bar with less than 5 years since the first date of installation on any helicopter, within the compliance time shown in Table 1 to paragraph (e)(1) of this AD:
(i) Remove the torsion bar and, using a magnifying glass with a maximum magnification level of 10X, visually inspect for a crack in the polyurethane (PU) coating of the torsion bar as depicted in Figure 1 of Gazelle Inspection—Check 65.12.607, “Main Rotor Head: Torsion Tie-Back Check (Post MOD 076171),” dated August 2008, of the Eurocopter Gazelle Helicopter Maintenance Manual, Tome 1. This type of task is commonly called a “work card” and will be referenced in this AD as “the work card.” Consider two cracks that are less than 5 mm (.196 in) apart as a single crack. If there is a crack in the PU coating that is more than 5 mm (.196 in), replace the torsion bar before further flight. Do not rework the PU coating of the torsion bar in any way.
(ii) Inspect the angle, dimension alpha, as depicted in View on Arrow F of Figure 1 of the work card. If the angle is 7 or more degrees, replace the torsion bar before further flight.
(iii) Inspect each bushing for corrosion on the inside diameter. If any corrosion cannot be removed by rubbing it with an abrasive pad, replace the torsion bar before further flight.
(iv) Using an outside micrometer, measure the thickness, dimension a, of each bushing as depicted in Detail AA of Figure 1 of the work card. If the thickness is less than 37.520 mm (1.477 in), replace the torsion bar before further flight.
(v) Using an inside micrometer, measure the inside diameter, dimension b, of each bushing as depicted in Detail AA of Figure 1 of the work card. If the diameter is larger than 21.040 mm (.828 in), replace the torsion bar before further flight.
(vi) Inspect the two faces of each bushing for missing varnish. If varnish is missing from more than 15% of the surface area on a face of a bushing, before further flight, remove all varnish using 400-grit abrasive paper. Finish with an abrasive pad and apply a coat of P05 paint to the face of the bushing.
| Time accumulated on torsion bar | Compliance time |
|---|---|
| (i) Less than 320 hours time-in-service (TIS) since new and has never been inspected in accordance with Airbus Helicopters 341G—342J Airworthiness Limitations, Revision 18, dated June 2014 (limitations inspection) | Before accumulating 420 hours TIS since new or within 24 months since the date of first installation on any helicopter, whichever occurs first. |
| (ii) 320 or more hours TIS since new and has never had a limitations inspection | Within 100 hours TIS, or before accumulating 600 hours TIS since new, or within 24 months since the date of first installation on any helicopter, whichever occurs first. |
| (iii) Less than 320 hours TIS since the last limitations inspection | Before accumulating 420 hours TIS since the last limitations inspection or within 24 months since the last limitations inspection, whichever occurs first. |
| (iv) 320 or more hours TIS since the last limitations inspection | Within 100 hours TIS, or before accumulating 600 hours TIS since the last limitations inspection, or within 24 months since the last limitations inspection, whichever occurs first. |
(2) For each torsion bar with 5 or more years since the first date of installation on any helicopter, within the compliance time shown in Table 2 to paragraph (e)(2) of this AD, do the inspections required by paragraphs (e)(1)(i) through (vi) of this AD.
| Time accumulated on torsion bar | Compliance time |
|---|---|
| (i) Less than 320 hours TIS since new, and less than 6 months since the date of first installation on any helicopter, and has never had a limitations inspection | Before accumulating 420 hours TIS since new or within 12 months since the date of first installation on any helicopter, whichever occurs first. |
| (ii) 320 or more hours TIS since new or more than 6 months since the date of first installation on any helicopter, and has never had a limitations inspection | Within 100 hours TIS, or within 6 months, or before accumulating 600 hours TIS since new, or within 24 months since the date of first installation on any helicopter, whichever occurs first. |
| (iii) Less than 320 hours TIS since last limitations inspection and less than 6 months since the last limitations inspection | Before accumulating 420 hours TIS since last limitations inspection or 12 months since last limitations inspection, whichever occurs first. |
| (iv) 320 or more hours TIS since last limitations inspection or 6 or more months since the last limitations inspection | Within 100 hours TIS, or within 6 months, or before accumulating 600 hours TIS since the last limitations inspection, or within 24 months since the last limitations inspection, whichever occurs first. |
(3) Repeat the inspections required by paragraphs (e)(1)(i) through (vi) of this AD as follows:
(i) For torsion bars with less than 6 years since the date of installation on any helicopter, at intervals not to exceed 420 hours TIS or 24 months, whichever occurs first.
(ii) For torsion bars with 6 or more years since the date of installation on any helicopter, at intervals not to exceed 420 hours TIS or 12 months, whichever comes first.
