Airworthiness Directive · Amendment 39-22453 · Ground proximity system
Various Helicopters
This AD applies to all helicopters, certificated in any category, equipped with a radio (also known as radar) altimeter. These radio altimeters are installed on various helicopter models including, but not limited to, the helicopters for which the design approval holder is identified in paragraphs (c)(1) through (20) of this AD.
(1) Airbus Helicopters
(2) Airbus Helicopters Deutschland GmbH
(3) Air Space Design and Manufacturing, LLC
(4) Bell Textron Canada Limited
(5) Bell Textron Inc.
(6) Brantly International, Inc.
(7) Centerpointe Aerospace Inc.
(8) Columbia Helicopters, Inc.
(9) The Enstrom Helicopter Corporation
(10) Erickson Air-Crane Incorporated, DBA Erickson Air-Crane
(11) Helicopteres Guimbal
(12) Siam Hiller Holdings, Inc.
(13) Kaman Aerospace Corporation
(14) Leonardo S.p.a.
(15) MD Helicopters Inc.
(16) PZL Swidnik S.A.
(17) Robinson Helicopter Company
(18) Schweizer RSG LLC
(19) Scotts-Bell 47 Inc.
(20) Sikorsky Aircraft Corporation
The FAA is superseding Airworthiness Directive (AD) 2021-23- 13, which applied to all helicopters equipped with a radio (also known as radar) altimeter. AD 2021-23-13 required revising the limitations section of the existing rotorcraft flight manual (RFM) for your helicopter to incorporate limitations prohibiting certain operations requiring radio altimeter data when in the presence of 5G C-Band interference in areas as identified by Notices to Air Missions (NOTAMs). Since the FAA issued AD 2021-23-13, the FAA determined that additional limitations are needed due to the continued deployment of new 5G C-Band base stations whose signals are expected to cover most of the contiguous United States at transmission frequencies between 3.7- 3.98 GHz (5G C-Band). This AD requires revising the limitations section of the existing RFM to incorporate limitations prohibiting certain operations requiring radio altimeter data, due to the presence of 5G C- Band interference. The FAA is issuing this AD to address the unsafe condition on these products. In addition, the FAA is requesting comment on the change to the spurious emission level requirement.
(1) For purposes of this AD, a “radio altimeter tolerant rotorcraft” is one for which the radio altimeter, as installed, demonstrates the tolerances specified in paragraphs (g)(1)(i) and (ii) of this AD, using a method approved by the FAA. No actions are required by this AD for radio altimeter tolerant rotorcraft.
(i) Tolerance to radio altimeter interference, for the fundamental emissions (3.7-3.8 GHz), at or above the power spectral density (PSD) curve threshold specified in figure 1 to paragraph (g)(1)(i) of this AD.
Figure 1 to paragraph (g)(1)(i)— Fundamental Effective Isotropic PSD at Outside Interface of Rotorcraft Antenna
(ii) Tolerance to radio altimeter interference, for the spurious emissions (4.2-4.4 GHz), at or above the PSD curve threshold specified in figure 2 to paragraph (g)(1)(ii) of this AD.
Figure 2 to paragraph (g)(1)(ii): Spurious Effective Isotropic PSD at Outside Interface of Rotorcraft Antenna
(2) For purposes of this AD, a “non-radio altimeter tolerant rotorcraft” is one for which the radio altimeter, as installed, does not demonstrate the tolerances specified in paragraphs (g)(1)(i) and (ii) of this AD.
For non-radio altimeter tolerant rotorcraft: On or before January 4, 2022, revise the Limitations Section of the existing RFM for your helicopter by incorporating the limitations specified in figure 3 to paragraph (h) of this AD. This may be done by inserting a copy of this AD into the existing RFM for your helicopter. The action required by this paragraph may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9(a)(1) through (4) and 14 CFR 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417 or 14 CFR 135.439.
Figure 3 to paragraph (h)— RFM Revision
For non-radio altimeter tolerant rotorcraft, do the actions specified in paragraphs (i)(1) and (2) of this AD.
(1) On or before June 30, 2023, revise the Limitations Section of the existing RFM for your helicopter by including the information specified in figure 4 to paragraph (i) of this AD. This may be done by inserting a copy of this AD into the existing RFM for your helicopter. The action required by this paragraph may be performed by the owner/operator (pilot) holding at least a private pilot certificate and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9(a)(1) through (4) and 14 CFR 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417 or 14 CFR 135.439. Incorporating the RFM revision required by this paragraph terminates the RFM revision required by paragraph (h) of this AD.
(2) Before further flight after incorporating the limitations specified in figure 4 to paragraph (i) of this AD, remove the RFM revision required by paragraph (h) of this AD.
Figure 4 to paragraph (i)— RFM Revision for Non-Radio Altimeter Tolerant Rotorcraft
(1) Modifying the rotorcraft from a non-radio altimeter tolerant rotorcraft to a radio altimeter tolerant rotorcraft terminates the limitations in paragraph (i) of this AD for that rotorcraft.
(2) After modifying the rotorcraft to a radio altimeter tolerant rotorcraft, the limitations specified by paragraph (i) of this AD may be removed from the RFM.
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.
Appliances and equipment
