Airworthiness Directive · Amendment 39-11528 · Agusta S.p.A. (Agusta) Model AB412 Helicopters
Agusta S.p.A. (Agusta) Model AB412 Helicopters
Model AB412 helicopters with rescue hoist, part number BL10300-60 or BL10300-59, installed, certificated in any category.
Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.
This amendment adopts a new airworthiness directive (AD) that is applicable to Agusta Model AB412 helicopters with certain rescue hoists installed. This action requires replacing the rescue hoist hook assembly retention pin (retention pin) and periodically inspecting the rescue hoist. This amendment is prompted by an incident in which a rescue hoist hook assembly separated from a helicopter due to a missing retention pin. The actions specified in this AD are intended to prevent separation of the rescue hoist hook assembly from the helicopter due to failure of the retention pin. Loss of the rescue hoist hook assembly could result in loss of the person on the rescue hoist. Also, with the loss of the weight of the hoist cable assembly, the rescue hoist cable could become entangled with a main rotor or tail rotor blade, and result in damage or separation of a rotor blade and subsequent loss of control of the helicopter.
To prevent separation of the rescue hoist hook assembly from the helicopter due failure of the rescue hoist hook assembly retention pin (retention pin), accomplish the following:
(a) Before further flight, replace the retention pin, part number (P/N) BL2395, of the rescue hoist hook assembly, P/N S6150-61090-1, as follows:
(1) Disconnect the helicopter battery and ensure the external electrical power is not connected.
(2) Remove the safety wire and remove and discard the retention pin. Retain the two washers, P/N AN960C816L, for reuse (Figure 1).
(3) Install a zero-hours time-in-service (TIS) retention pin, P/N BL2395, and the two washers, P/N AN960C816L, (Figure 1). Safety wire the retention pin to the hook assembly using safety wire, P/N MS 20995C32.
(b) Before further flight, and thereafter prior to each flight in which the rescue hoist will be operated:
(1) Inspect the rescue hoist for oil leakages and proper electrical and mechanical connections.
(2) Inspect the retention pin, P/N BL2395, of the ring assembly, P/N BL2441, for safety wire integrity.
(3) Inspect the pin, P/N NAS516C4-6 or P/N MS171524, installed on the housing, P/N BL1357-1, and verify the absence of any rotation between the housing and the adapter, P/N BL1355, (Figure 1).
(4) Inspect the rescue hoist hook to ensure it rotates freely relative to the housing (number 3 on Figure 1).
(5) Correct any discrepancies found in step (1), (2), (3), or (4).
(c) At intervals not to exceed 25 hours time-in-service (TIS), inspect the rescue hoist as follows:
(1) Inspect the attachment and support for cracks, wear, corrosion, damage, and security. Replace any parts that have cracks, wear, corrosion, or damage with an airworthy part.
(2) Inspect the cable for fraying, wear, and corrosion. If fraying, wear, or corrosion is found, replace the cable with an airworthy cable.
(3) Inspect the cable for proper routing through the guide rollers, pulley, and drum. Correct cable routing if necessary.
(d) At intervals not to exceed 12 calendar months, inspect the retention pin as follows:
(1) Referring to Figure 1, remove the safety wire and the retention pin. Retain the two washers, P/N AN960C816L, for re-use. Inspect the retention pin for scratches or deformations. If a scratch or deformation is found, replace the retention pin with an airworthy retention pin.
(2) Install the retention pin and the two washers, P/N AN960C816L, (Figure 1). Safety wire the retention pin to the hook assembly using safety wire, P/N MS20995C32.
