Airworthiness Directive · Amendment 39-15911 · Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
Eurocopter Deutschland GmbH (ECD) Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 Helicopters
This AD applies to Model MBB-BK 117 A-1, A-3, A-4, B-1, B-2, and C-1 helicopters, certificated in any category, with the following main rotor blade (blade) installed:
| 117-15001 |
| 117-150021 |
| 117-150061 |
| 117-151321 |
| 117-151341, 117-151341V001 |
| 117-151351, 117-151351V001 |
| 117-151361, 117-151361V001 |
| 117-151421V001 |
| 117-151441, 117-151441V001 |
| 117-151441V002, 117-151441V003 |
| 117-151451, 117-151451V001 |
| 117-151451V002, 117-151451V003 |
| 117-151461, 117-151461V001 |
We are superseding an existing airworthiness directive (AD) for the specified ECD model helicopters that currently requires initial and repetitive inspections of the main rotor blade (blade) upper and lower surfaces for bulging. This AD results from mandatory continuing airworthiness information (MCAI) issued by the European Aviation Safety Agency (EASA), which is the Technical Agent for the Member States of the European Community, based on reported incidents in which a balance weight migrated toward the tip of the blade. The MCAI states that new blades have become available that are not fitted with lead balance weights. The MCAI states that only blades equipped with a lead balance weight may result in the unsafe condition. This AD retains the requirements of the current AD but limits the applicability to those part-numbered blades that are fitted with lead balance weights. The actions are intended to limit the applicability to those blades fitted with lead balance weights that could detach, migrate, and cause severe vibrations leading to blade failure and subsequent loss of control of the helicopter.
Required as indicated:
(1) Within 5 hours time-in-service (TIS), unless already done, and thereafter at intervals not to exceed 50 hours TIS, visually inspect the upper and lower surfaces of each affected main rotor blade (blade) in the area of the outboard lead balance weight in the marked inspection area for bulging.
(i) If a marked inspection area is not visible, mark the area using a water-resistant and indelible marking pencil and then inspect the upper and lower surfaces of each blade in the area of the outboard lead balance weight for bulging.
Note: For guidance, the current MBB-BK117 Maintenance Manual at Figure 14-5A contains the dimensions and placement of the inspection area.
(ii) If bulging exceeds 1 millimeter (mm) (0.040 inch) in height, before further flight, remove the blade and replace it with an airworthy blade that is not listed in the applicability of this AD.
(2) Replacing the affected blade with an airworthy blade that is not listed in the applicability of this AD is terminating action for the requirements of this AD.
We refer to flight hours as hours TIS. We retained the compliance time from the current AD and the Eurocopter ASB, dated August 18, 1994, and did not include the option of accumulating 1,800 flight hours since the first flight as stated in the MCAI. We do not incorporate ASB, Revision 3, damage inspection. We do not require that you contact ECD for instructions for corrective action. This AD requires that you contact the FAA for an Alternate Method of Compliance.
Alternative Methods of Compliance (AMOCs): The Manager, Safety Management Group, FAA, ATTN: Sharon Miles, Aviation Safety Engineer, Rotorcraft Directorate, Regulations and Guidance Group, Fort Worth, Texas 76193-0111, telephone (817) 222-5122, fax (817) 222-5961, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19.
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.
