Daily Rules, Proposed Rules, and Notices of the Federal Government
For service information identified in this proposed AD, contact Boeing Commercial Airplanes,
You may examine the AD docket on the Internet at
We invite you to send any written relevant data, views, or arguments about this proposal. Send your comments to an address listed under the
We will post all comments we receive, without change, to
The Model 737 airplanes cabin altitude warning is an intermittent horn that sounds when cabin altitude exceeds 10,000 feet. The same intermittent warning horn sound is used by the takeoff configuration warning system (TCWS) to warn of an unsafe airplane configuration for takeoff. The TCWS warning functionality is inhibited by air/ground logic when the airplane is in flight. However, the Model 737 airplane's cabin altitude warning system design does not currently incorporate a dedicated means of positively identifying the warning horn as a cabin altitude warning or a takeoff configuration warning. There are approximately 25 known instances where flightcrews misinterpreted a valid cabin altitude warning as a takeoff configuration warning.
Failure of the flightcrew to recognize and react to a valid cabin altitude warning horn could result in incapacitation of the flightcrew due to hypoxia (lack of oxygen in the body), and consequent loss of control of the airplane. To address this unsafe condition, we issued the following ADs.
On July 7, 2003, we issued related AD 2003-14-08, Amendment 39-13227 (68 FR 41519, July 14, 2003). That AD applies to all Boeing Model 737-600, 737-700, 737-700C, 737-800, 737-900, 757, and 767 series airplanes. That AD requires revising the airplane flight manual (AFM) to advise the flightcrew to don oxygen masks as a first and immediate step when a cabin altitude warning occurs.
On June 15, 2006, we issued related AD 2006-13-13, Amendment 39-14666 (71 FR 35781, June 22, 2006). (A correction of that AD was published in the
On October 24, 2008, we issued related AD 2008-23-07, Amendment 39-15728 (73 FR 66512, November 10, 2008), for all Model 737 airplanes. That AD requires revising the AFM to include a new flightcrew briefing that must be done before the first flight of the day and following any change in flightcrew members, and to advise the flightcrew of this additional briefing. That AD resulted from continuing reports that flightcrews have failed to recognize and react properly to the cabin altitude warning horn.
The preambles to AD 2006-13-13 and AD 2008-23-07 explain that the revisions to the AFM required by those ADs are considered to be interim action. The manufacturer had advised us that it was developing a design change in the cabin altitude warning system that would address the identified unsafe condition(s), and that once this design change was developed, approved, and available, the FAA might consider additional rulemaking. The manufacturer now has developed such a modification, and we have determined that further rulemaking is necessary; this proposed AD follows from that determination. We can better ensure long-term continued operational safety by modifications or design changes to remove the source of the problem, rather than by AFM revisions alone.
We reviewed Boeing Alert Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010. The service information describes procedures for installing two warning level indicator lights on each of the P1-3 and P3-1 instrument panels in the flight compartment. The installation includes installing a new circuit breaker and changing certain wire bundles.
We are proposing this AD because we evaluated all the relevant information and determined the unsafe condition described previously is likely to exist or develop in other products of the same type design.
This proposed AD would require accomplishing the actions specified in the service information described previously, except as discussed under “Difference Between the Proposed AD and the Service Information.” The proposed AD would also require revising the Limitations Section of the AFM to remove certain requirements of previous AD actions, and to advise the flightcrew of the following changes: Revised non-normal procedures to use when a cabin altitude warning or rapid depressurization occurs, and revised cabin pressurization procedures for normal operations.
The effectivity in Boeing Alert Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010, identifies Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes; however, it does not include all applicable serial numbers for airplanes that are subject to the identified unsafe condition. The actions for Group 1 airplanes, as specified in this service bulletin, must be done on additional airplanes, as identified in the applicability of this proposed AD.
Groups 8 through 21 airplanes are also included in the effectivity of the service bulletin; however, the actions required by this proposed AD would affect only Groups 1 through 7 airplanes. Therefore, concurrent actions, which specify installing a new P5-16 cabin altitude and rate of climb panel and cabin altitude and differential pressure indicator, would not be required by this proposed AD.
We estimate that this proposed AD would affect 650 airplanes of U.S. registry. The following table provides the estimated costs for U.S. operators to comply with this proposed AD.
Title 49 of the United States Code specifies the FAA's authority to issue rules on aviation safety. Subtitle I, section 106, describes the authority of the FAA Administrator. Subtitle VII: Aviation Programs, describes in more detail the scope of the Agency's authority.
We are issuing this rulemaking under the authority described in Subtitle VII, Part A, Subpart III, Section 44701: “General requirements.” Under that section, Congress charges the FAA with promoting safe flight of civil aircraft in air commerce by prescribing regulations for practices, methods, and procedures the Administrator finds necessary for safety in air commerce. This regulation is within the scope of that authority because it addresses an unsafe condition that is likely to exist or develop on products identified in this rulemaking action.
We determined that this proposed AD would not have federalism implications under Executive Order 13132. This proposed AD would 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.
(1) Is not a “significant regulatory action” under Executive Order 12866,
(2) Is not a “significant rule” under the DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979),
(3) Will not affect intrastate aviation in Alaska, and
(4) Will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act.
Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.
Accordingly, under the authority delegated to me by the Administrator, the FAA proposes to amend 14 CFR part 39 as follows:
1. The authority citation for part 39 continues to read as follows:
49 U.S.C. 106(g), 40113, 44701.
2. The FAA amends § 39.13 by adding the following new airworthiness directive (AD): Docket No. FAA-2011-0258; Directorate Identifier 2010-NM-191-AD.
(a) We must receive comments by May 9, 2011.
(b) This AD affects the ADs identified in paragraphs (b)(1), (b)(2), and (b)(3) of this AD. This AD does not supersede the requirements of these ADs.
(1) AD 2003-14-08, Amendment 39-13227.
(2) AD 2006-13-13, Amendment 39-14666.
(3) AD 2008-23-07, Amendment 39-15728.
(c) This AD applies to The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes, Groups 1 through 7 airplanes, certificated in any category; identified in Boeing Alert Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010; or having any serial number identified in table 1 of this AD.
(d) Air Transport Association (ATA) of America Code 31, Instruments.
(e) This AD was prompted by a design change in the cabin altitude warning system that would address the identified unsafe condition. The Federal Aviation Administration is issuing this AD to prevent failure of the flightcrew to recognize and react to a valid cabin altitude warning horn, which could result in incapacitation of the flightcrew due to hypoxia (lack of oxygen in the body) and consequent loss of control of the airplane.
(f) Comply with this AD within the compliance times specified, unless already done.
(g) For Groups 1 through 7 airplanes, as identified in Boeing Alert Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010; and airplanes having any serial number identified in table 1 of this AD: Within 36 months after the effective date of this AD, install two warning level indicator lights on each of the P1-3 and P3-1 instrument panels in the flight compartment, in accordance with the Accomplishment Instructions of Boeing Alert Service Bulletin 737-31A1332, Revision 1, dated June 24, 2010. The actions required for Group 1 airplanes also apply to the airplanes identified in table 1 of this AD.
(h) Before further flight after doing the installation required by paragraph (g) of this AD, do the actions specified in paragraphs (h)(1), (h)(2), and (h)(3) of this AD.
(1) Revise the Limitations Section of the applicable Boeing 737 AFM by doing the following action: Delete the “CABIN ALTITUDE WARNING TAKEOFF BRIEFING” added by AD 2008-23-07, Amendment 39-15728.
(2) Revise the Non-Normal Procedures Section of the applicable Boeing 737
(i) Delete the procedure “WARNING HORN—CABIN ALTITUDE OR CONFIGURATION” added by AD 2006-13-13, Amendment 39-14666. If the title of this procedure has been changed according to FAA alternative method of compliance (AMOC) letter 130S-09-134a, dated April 28, 2009, delete the procedure that was approved according to this AMOC letter.
(ii) Delete the procedure entitled “CABIN ALTITUDE WARNING OR RAPID DEPRESSURIZATION” added by AD 2003-14-08, Amendment 39-13227.
(iii) If the procedure entitled “CABIN ALTITUDE (Airplanes with the CABIN ALTITUDE lights installed)” is currently contained in the applicable Boeing 737 AFM, delete the procedure entitled “CABIN ALTITUDE (Airplanes with the CABIN ALTITUDE lights installed).”
(iv) Add the following statement. This may be done by inserting a copy of this AD into the applicable AFM.
(3) Revise the Normal Procedures Section of the applicable Boeing 737 AFM by doing the actions specified in paragraphs (h)(3)(i) and (h)(3)(ii) of this AD.
(i) Delete the “CABIN ALTITUDE WARNING TAKEOFF BRIEFING” procedure added by AD 2008-23-07.
(ii) Add the following statement. This may be done by inserting a copy of this AD into the applicable AFM.
“For normal operations, the pressurization mode selector should be in AUTO prior to takeoff.
When statements identical to those specified in paragraphs (h)(2)(iv) and (h)(3)(ii) of this AD have been included in the general revisions of the AFM, the general revisions may be inserted into the AFM, and the copies of this AD may be removed from the AFM.
(i) Accomplishment of the requirements of this AD terminates the requirements of the ADs identified in paragraphs (i)(1), (i)(2), and (i)(3) of this AD for only the airplanes identified in paragraph (c) of this AD.
(1) AD 2003-14-08: The requirements specified in Table 1 and Figure 1 of that AD.
(2) AD 2008-23-07: All requirements of that AD.
(3) AD 2006-13-13: All requirements of that AD.
(j) Special flight permits, as described in Section 21.197 and Section 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199), are not allowed.
(k)(1) The Manager, Seattle ACO, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the ACO, send it to the attention of the person identified in the Related Information section of this AD. Information may be e-mailed to:
(2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office.
(l) For more information about this AD, contact Jeffrey W. Palmer, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356;
(m) For service information identified in this AD, contact Boeing Commercial Airplanes, Attention: Data & Services Management, P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-544-5000, extension 1, fax 206-766-5680; e-mail