Airworthiness directives › 2025-04-08
AD 2025-04-08 Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier Inc.) Airplanes
Applicability*9
This AD applies to the MHI RJ Aviation ULC (Type Certificate previously held by Bombardier Inc.) airplanes identified in paragraphs (c)(1) through (6) of this AD, certificated in any category, that are equipped with a radio altimeter and not determined to be a radio altimeter tolerant airplane as defined in paragraph (g) of this AD. (1) Model CL-600-2B19 (Regional Jet Series 100 and 440) airplanes, serial number (S/N) 7002 through 8113. (2) Model CL-600-2C10 (Regional Jet Series 700, 701, and 702) airplanes, S/N 10002 through 10999. (3) Model CL-600-2C11 (Regional Jet Series 550) airplanes, S/N 10002 through 10999. (4) Model CL-600-2D15 (Regional Jet Series 705) airplanes, S/N 15001 through 15990. (5) Model CL-600-2D24 (Regional Jet Series 900) airplanes, S/N 15001 through 15990. (6) Model CL-600-2E25 (Regional Jet Series 1000) airplanes, S/N 19013 through 19990.
Compliance
Comply with this AD within the compliance times specified, unless already done.
Required actions
For purposes of this AD, a “radio altimeter tolerant airplane” is one for which the radio altimeter, as installed, demonstrates the tolerances specified in paragraphs (g)(1) and (2) of this AD, using a method approved by the FAA. No actions are required by this AD for radio altimeter tolerant airplanes. (1) Tolerance to radio altimeter interference, for the fundamental emissions (3.7-3.98 GHz), at or above the power spectral density (PSD) curve threshold specified in figure 1 to paragraph (g)(1) of this AD. Figure 1 to Paragraph (g)(1)—Fundamental Effective Isotropic PSD at Outside Interface of Airplane Antenna BILLING CODE 4910-13-P ER21MR25.000 (2) 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)(2) of this AD. Figure 2 to Paragraph (g)(2)—Spurious Effective Isotropic PSD at Outside Interface of Airplane Antenna ER21MR25.001 BILLING CODE 4910-13-C
Unsafe condition
This AD was prompted by the determination that radio altimeters cannot be relied upon to perform their intended function if they experience interference from wireless broadband operations in the 3.7-3.98 GHz frequency band (5G C-Band). The FAA is issuing this AD because radio altimeter anomalies can result in the inhibition of certain failure messages such that the flightcrew are unable to perform appropriate airplane flight manual procedures in the time needed to prevent potential ignition hazard due to overheated hydraulic fluid circulating in the fuel tanks area, which may lead to loss of continued safe flight and landing, and/or structural deformation of the wing leading edge which may reduce the safety margin (to stall).
Affected ADs
None.
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