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Federal Register / Vol. 86, No. 47 / Friday, March 12, 2021 / Rules and Regulations Mandatory Continuing Airworthiness Information, or the MCAI, to correct an unsafe condition for all Airbus Helicopters Model AS 350 B, AS 350
BA, AS 350 BB, AS 350 B1, AS 350 B2, AS 350 B3, and AS 350 D helicopters;
AS 355 E, AS 355 F, AS 355 F1, AS 355
F2, AS 355 N, and AS 355 NP
helicopters; and EC 130 B4 and EC 130
T2 helicopters. Model AS 350 BB
helicopters are not certificated by the FAA and are not included on the U.S.
type certificate data sheet; this AD
therefore does not include those helicopters in the applicability. This AD
also applies to Airbus Helicopter Model AS 350C helicopters because these helicopters have a similar design and are included on the U.S. type certificate data sheet.
The FAA issued a notice of proposed rulemaking NPRM to amend 14 CFR
part 39 by adding an AD that would apply to all Airbus Helicopters Model AS350B, AS350BA, AS350B1, AS350B2, AS350B3, AS350C, and AS350D helicopters; Model AS355E, AS355F, AS355F1, AS355F2, AS355N, and AS355NP helicopters; and Model EC130B4 and EC130T2 helicopters. The NPRM published in the Federal Register on December 15, 2020 85 FR
81157. The NPRM was prompted by a report of failed main rotor hub-to-mast attachment screws. The NPRM proposed to require determining whether the helicopter has been operated in a severe environment since the last inspection of the main rotor hub-to-mast attachment screws, an inspection of the main rotor hub-to-mast attachment screws if the
helicopter has been operated in a severe environment, and replacement of the main rotor hub-to-mast attachment screws if necessary, as specified in an EASA AD.
The FAA is issuing this AD to address failed main rotor hub-to-mast attachment screws, which could lead to disconnection of the main rotor hub-tomast attachment, possibly resulting in loss of control of the helicopter. See the MCAI for additional background information.
Comments The FAA gave the public the opportunity to participate in developing this final rule. The FAA has considered the comments received. An individual indicated agreement with the NPRM.
Conclusion The FAA reviewed the relevant data, considered the comment received, and determined that air safety and the public interest require adopting this final rule as proposed, except for minor editorial changes. The FAA has determined that these minor changes:
Are consistent with the intent that was proposed in the NPRM for addressing the unsafe condition; and Do not add any additional burden upon the public than was already proposed in the NPRM.
Related Service Information Under 1
CFR Part 51
EASA AD 20170032 describes procedures for determining whether the helicopter has been operated in a severe environment since the last inspection of
the main rotor hub-to-mast attachment screws, an inspection of the main rotor hub-to-mast attachment screws for corrosion and damage damage includes cracks, dents, and bolt distortion if the helicopter was operated in a severe environment, and replacement of the main rotor hub-to-mast attachment screws if necessary. This material is reasonably available because the interested parties have access to it through their normal course of business or by the means identified in the ADDRESSES section.
Differences Between This AD and the MCAI
EASA AD 20170032 does not apply to Airbus Helicopter Model AS350C
helicopters, which are included on the U.S. type certificate data sheet.
However, this AD applies to Airbus Helicopter Model AS350C helicopters because those helicopters have a similar design to the helicopters identified in EASA AD 20170032.
Where the service information specified in paragraph 3 of EASA AD
20170032 specifies to contact Airbus Helicopters if damage or corrosion exceeds existing criteria, this AD
requires replacing the affected screws using a method approved by the Manager, International Validation Branch, FAA.
Costs of Compliance The FAA estimates that this AD
affects 1,220 helicopters of U.S. registry.
The FAA estimates the following costs to comply with this AD:

ESTIMATED COSTS FOR REQUIRED DETERMINATION OF HELICOPTER OPERATION IN A SEVERE ENVIRONMENT
Labor cost
Parts cost
Cost per product
Cost on U.S.
operators
1 work-hours $85 per hour = $85

$0

$85

$103,700

The FAA estimates that it would take about 1 hour per product to comply with the reporting requirement in this AD. The average labor rate is $85 per hour. Based on these figures, the FAA
estimates the cost of reporting the inspection results on U.S. operators to be $103,700, or $85 per product.

The FAA estimates the following costs to do any necessary on-condition actions that would be required based on the results of any required actions. If a helicopter is determined to have been operated in a severe environment, an inspection of the main rotor hub-to-mast attachment screws will be required. If
there is corrosion or damage to any of the screws, replacement of the affected screws will be required. The FAA has no way of determining the number of aircraft that might need these oncondition actions:

ESTIMATED COSTS OF ON-CONDITION ACTIONS
Labor cost
Parts cost
Cost per product
4 work-hours $85 per hour = $340

$106

$446

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