Airworthiness Directive · Amendment 39-17258 · Powerplant system
Agusta S.p.A. Helicopters
This AD applies to Model A109E helicopters, up to and including serial number (S/N) 11694, except 11633 and 11634; and Model A109S helicopters, up to and including S/N 22034, except S/N 22026 and 22033; with lower semichannel assemblies, part number (P/N) 109-0641-10-213 or 109-0642-01-171, installed; certificated in any category.
Note to paragraph (a) of this AD: The lower semichannel assemblies are sub-components of the forward firewall assembly.
We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model A109E and Model A109S helicopters with certain lower semichannel assemblies installed. This AD requires a one-time inspection of the lower semichannel assemblies to determine if metallic spacers are installed. If the metallic spacers are installed, this AD requires an inspection for the correct installation of the metallic spacers on the semichannels and for the correct seating of the gaskets. If the metallic spacers are not installed with rivets, the lower semichannel assemblies must be modified, and the main drive shaft must be inspected for damage. This AD was prompted by reports of damage to the main drive shaft caused by improperly secured metallic spacers on some A109 model helicopters. The actions of this AD are intended to detect missing spacer rivets, which could allow the metallic spacers to rotate and lead to damage and failure of the main drive shaft, and subsequent 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.
Within 50 hours time-in-service:
(1) Inspect the left-side and right-side lower semichannel assemblies by referring to Figures 1 and 2, and in accordance with Paragraph 3. of the Compliance Instructions in the Agusta Bollettino Tecnico (BT) No. 109EP-79 for the Model A109E helicopter, or BT No. 109S-15 for the Model A109S helicopter, both dated July 12, 2007, to determine if metallic spacers, P/N 109-0642-01-195, are installed. If metallic spacers are not installed, no further actions are required.
(2) For each semichannel assembly with a metallic spacer, remove the semichannel assembly from the helicopter firewall and note whether it is the left-side or right-side semichannel assembly.
(3) Inspect each removed semichannel assembly and determine whether there is a fixing rivet, P/N MS20427M3-5, MS20426T3-5, or A298A04TW02, installed that holds the spacer to the lower semichannel assembly and whether the gasket is properly seated.
(4) For each semichannel assembly without a fixing rivet on each side of the lower semichannel assembly or those where the gasket is improperly seated, separate the lower semichannel from the upper semichannel, noting the orientation of each spacer and gasket. Modify the lower semichannel assembly by installing a fixing rivet on each side of the lower semichannel assembly, and reattaching the lower and upper semichannel assemblies in accordance with paragraphs 4.2 through 4.7 of the appropriate BT for your model helicopter. Paragraph 4.2 of the BT states “remove the fixing rivets”; this AD changes that provision to “remove the screws, P/N MS27039-08-05.”
(5) Inspect each main drive shaft for a nick, a scratch, or other damage in the semichannel area. If a nick, a scratch, or other damage is found that exceeds those allowable damage tolerances in the maintenance manual, replace the main drive shaft with an airworthy main drive shaft.
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.
Aircraft
