Airworthiness Directive · Amendment 39-19901 · Main rotor gearbox
PZL Swidnik S.A. Helicopters
This AD applies to PZL Swidnik S.A. (PZL) Model PZL W-3A helicopters, certificated in any category, with a WR-3 main gearbox (MGB) with a serial number (S/N) up to 316463007M inclusive and with a bolt part number (P/N) 89.00.0049 and washer P/N 89.06.0387, installed.
The FAA is adopting a new airworthiness directive (AD) for PZL Swidnik S.A. (PZL) Model PZL W-3A helicopters. This AD requires inspecting the main gearbox (MGB) bolts and washers to determine if they are properly locked and, depending on the inspection outcome, removing the engine, removing certain bolts from service, and performing more in-depth inspections; and depending on the outcome of those inspections, replacing the graphite seal assembly or removing it from service. Finally, this AD prohibits installing any affected MGB on a helicopter unless it has met the requirements of this AD. This AD was prompted by reports that the bolts securing the input quill and graphite seal assembly of the MGB were not properly locked. The actions of this AD are intended to address an unsafe condition on these products.
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) Within 25 hours time-in-service (TIS), inspect each bolt to determine if it is properly locked with the washer by following Chapter II, Inspection Procedure, paragraphs 3.1.a) and 3.1.b) of WYTWÓRNIA SPRZĘTU KOMUNIKACYJNEGO “PZL-Świdnik” Spólka Akcyjna Mandatory Bulletin No. BO-37-18-289, dated October 23, 2018 (MB BO-37-18-289). If any bolt is not properly locked, before further flight:
(i) Remove the engine to visually inspect the bolt head for any sign of rubbing and deformation.
(ii) If there is no sign of rubbing or deformation, loosen the bolt and tighten to the correct torque value of 2.5-3.0 Nm. Lock the bolt by folding tabs of the washer up to the side surfaces of the bolt head. Photo 4 of MB BO-37-18-289 shows an example of a properly locked bolt.
(iii) If there is any sign of rubbing or deformation;
(A) Remove from service the bolt.
(B) Remove the left-hand (LH) and right-hand (RH) input drive quill seals by following paragraphs 1.1. through 1.6., Procedure—Case B. Attachment 1 to MB BO-37-18-289.
(C) Visually inspect each graphite seal assembly of the LH and RH input drive quill seals for any crack, damage, and surface deformation in the surface area identified as “D” of Sketch 3. Radial Seal, Attachment 1 to MB BO-37-18-289, and any crack, damage, surface deformation, cracked graphite segments and seizing of grooves in the surface area identified as “E” of Sketch 3. Radial Seal, Attachment 1 to MB BO-37-18-289. For purposes of this inspection, damage to the graphite seal assembly may be indicated by spalling, chipping, scratches, or dents. Also visually inspect for unsmooth freedom of radial motion of each graphite ring in the surface area identified as “E” of Sketch 3. Radial Seal, Attachment 1 to MB BO-37-18-289, any scratch and dent in the surface areas identified as “A” and “B” of Sketch 3. Radial Seal, Attachment 1 to MB BO-37-18-289, and seizing on the surface area identified as “C” of Sketch 3. Radial Seal, Attachment 1 to MB BO-37-18-289.
(1) If there is any crack, damage, or surface deformation in surface area “E” greater than an area of 1.5 mm 2 or a depth of 1mm, before further flight, remove from service the graphite seal assembly.
(2) If there is any spalling or chipping in surface area “E” that is equal to or less than an area of 1.5 mm 2 and a depth of 1 mm, or any scratch or dent in surface areas “A” or “B” or seizing in surface area “C” that is acceptable after blending material flashes, before further flight, replace the graphite seal assembly.
(3) If there is any crack, damage, or surface deformation on surface “D”, cracked graphite segments or seizing of grooves on surface “E”, any scratch or dent in surface areas “A” or “B” or seizing in surface area “C” that is not acceptable after blending material flashes, or radial motion of graphite rings is difficult and not smooth, before further flight, remove from service the graphite seal assembly.
(2) After the effective date of this AD, do not install a WR-3 MGB with an S/N up to 316463007M inclusive and with a bolt P/N 89.00.0049 and washer P/N 89.06.0387 on any PZL Model PZL W-3A helicopter, unless it has been inspected in accordance with the requirements of this AD.
