The FAA has received reports indicating that erroneous glideslope indications have occurred on certain Empresa Brasileira de Aeronautica S.A. (EMBRAER) Model EMB-145 series airplanes. In these incidents, the glideslope deviation indicator unexpectedly changed from a centered position to a hard-fly-down or hard-fly-up indication during an instrument landing system (ILS) approach. These incidents have been attributed to discrepancies of certain Honeywell Primus II NV-850 Navigation Receiver Modules that are part of the Honeywell Primus II RNZ-850/-851 Integrated Navigation Units installed on the affected airplanes. An affected navigation receiver module may produce an erroneous glideslope deviation indication when operating in a narrow range of cold temperatures with the glideslope receiver tuned to certain frequencies. An erroneous glideslope deviation indication could lead to the aircraft making an approach off the glideslope, which could result in impact with an obstacle or terrain.
Affected Honeywell Primus II RNZ-850/-851 Integrated Navigation Units are installed on numerous aircraft models. Affected aircraft models include, but are not limited to, BAE Systems (Operations) Limited (Jetstream) Model 4101 airplanes; Bombardier BD-700-1A10 series airplanes; Bombardier CL-215-6B11 (CL415 variant) series airplanes; Cessna Model 560, 560XL, and 650 airplanes; Dassault Model Mystere-Falcon 50 series airplanes; Dornier Model 328-100 and -300 series airplanes; EMBRAER Model EMB-135 series airplanes; Learjet Model 45 airplanes; Raytheon Model Hawker 800XP and Hawker 1000 airplanes; and Sikorsky Model S-76A, S-76B, and S-76C aircraft. All aircraft models equipped with affected integrated navigation units may be subject to the same unsafe condition revealed on the EMBRAER Model EMB-145 series airplanes.
Explanation of the Requirements of the Rule
Since an unsafe condition has been identified that is likely to exist or develop on otherairplanes of the same type design, this AD is being issued to ensure that the flightcrew has an accurate glideslope deviation indication. An erroneous glideslope deviation indication could lead to the aircraft making an approach off the glideslope, which could result in impact with an obstacle or terrain. As one alternative for compliance, this AD provides for a one-time inspection to determine whether an affected navigation receiver module is installed. In lieu of this inspection, and for aircraft with an affected navigation receiver module, the AD also requires revising the Limitations section of the aircraft flight manual to include new limitations for ILS approaches.
Relevant Technical Discussions
During the development of this AD, the FAA received information demonstrating that the planned AD would present significant operational difficulties for affected operators. First, we learned that accomplishing the inspection specified in paragraph (b) of this AD within the specified compliance time could result in service delays and out-of-service time for affected aircraft. We also received information that the revision to the Limitations section that we were considering was too restrictive for certain airplanes and would have an adverse impact on operations. Further, because a majority of the fleet of affected aircraft is expected to be equipped with an affected navigation receiver module, we found that the adverse impact of this AD would be widespread.
In light of this information, we held further discussions with the manufacturer of the subject parts and representatives of industry. Data presented during these discussions led us to reconsider the degree of urgency of the identified unsafe condition and the requirements of this AD.
Interim Action
This is considered to be interim action. The manufacturer has advised that it currently is developing a modification that will address the unsafe condition addressed by this AD. Once this modification is developed, approved, and available, the FAA may consider additional rulemaking.
Determination of Rule's Effective Date
Since a situation exists that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.
Comments Invited
Although this action is in the form of a final rule that involves requirements affecting flight safety and, thus, was not preceded by notice and an opportunity for public comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications shall identify the Rules Docket number and be submitted in triplicate to the address specified under the caption ADDRESSES. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
Submit comments using the following format:
Organize comments issue-by-issue. For example, discuss a request to change the compliance time and a request to change the service bulletin reference as two separate issues.
For each issue, state what specific change to the AD is being requested.
Include justification (e.g., reasons or data) for each request.
Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-publiccontact concerned with the substance of this AD will be filed in the Rules Docket.
Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket Number 2003-NM-41-AD." The postcard will be date stamped and returned to the commenter.
Regulatory Impact
The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132.
The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and that it is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket. A copy of it, if filed, may be obtained from the Rules Docket at the location provided under the caption ADDRESSES.
List of Subjects in 14 CFR Part 39
Air transportation, Aircraft, Aviation safety, Safety.
Adoption of the Amendment
Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:
PART 39-AIRWORTHINESS DIRECTIVES
1. The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13[Amended]
2. Section 39.13 is amended by adding the following new airworthiness directive: