06-5585. Airworthiness Directives; Boeing Model 737 Airplanes

AGENCY:

Federal Aviation Administration (FAA), Department of Transportation (DOT).

ACTION:

Final rule; request for comments.

SUMMARY:

The FAA is adopting a new airworthiness directive (AD) for all Boeing Model 737 airplanes. This AD requires revising the airplane flight manual to advise the flightcrew of improved procedures for pre-flight setup of the cabin pressurization system, as well as improved procedures for interpreting and responding to the cabin altitude/configuration warning horn. This AD results from reports that airplanes have failed to pressurize, and that the flightcrews failed to react properly to the cabin altitude warning horn. We are issuing this AD to prevent failure of the airplane to pressurize and subsequent 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 body) and consequent loss of airplane control.

DATES:

This AD becomes effective July 7, 2006.

We must receive comments on this AD by August 21, 2006.

ADDRESSES:

Use one of the following addresses to submit comments on this AD.

• DOT Docket Web site: Go to http://dms.dot.gov and follow the instructions for sending your comments electronically.
• Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your comments electronically.
• Mail: Docket Management Facility; U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590.
• Fax: [phone].
• Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Gregg Nesemeier, Aerospace Engineer, Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone [phone]; fax [phone].

SUPPLEMENTARY INFORMATION:

Discussion

We have received a report indicating that during the investigation by the Air Accident Investigation and Aviation Safety Board of Greece into the August 14, 2005, Helios Airways accident near Athens, Greece, it was found that the Boeing Model 737-300 series airplane was not pressurized during the climb from the departure airport, and the flightcrew subsequently became incapacitated. It appears that the pressurization mode selector was improperly set for flight, and that the flightcrew subsequently misinterpreted the cabin altitude warning horn as a takeoff configuration warning horn. This misinterpretation may have occurred because the same warning horn provides both warning functions on Model 737 airplanes.

In addition, the FAA has become aware of a number of other incidents involving Model 737 airplanes where the flightcrew reaction to a valid cabin altitude warning horn was delayed, either because the flightcrew misinterpreted the horn as a takeoff configuration warning horn, or because they did not immediately don their oxygen masks. Crew reaction may have been delayed because the cabin altitude warning system on Model 737 airplanes provides only the warning horn; no associated cabin altitude warning light is installed that activates concurrently with the warning horn.

Failure of the airplane to pressurize and subsequent failure of the flightcrew to recognize and react to a valid cabin altitude warning horn, if not corrected, could result in incapacitation of the flightcrew due to hypoxia (lack of oxygen in body) and consequent loss of airplane control.

Related Rulemaking

We have previously issued two ADs to address similar unsafe conditions.

On December 22, 2003, we issued AD 2003-03-15 R1, amendment 39-13366 (68 FR 64802, November 17, 2003), to require revising the AFM to advise the flightcrew to don oxygen masks as a first and immediate step when the cabin altitude warning occurs. That AD is applicable to various Boeing and McDonnell Douglas transport category airplanes, including Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes.

On July 14, 2003, we issued AD 2003-14-08, amendment 39-13227 (68 FR 41519, July 7, 2003), to require revising the AFM to require the same actions on various Boeing transport category airplanes, including Boeing 737-600, -700, -700C, -800, and -900 series airplanes.

In paragraph (a) of those ADs, a part of the revised text that we required to be placed in the AFMs of Model 737 airplanes reads “If the cabin altitude warning horn sounds: * * *” or “Condition: The cabin altitude warning horn sounds: * * *”, as applicable. Boeing has advised us that in light of the information given in the Discussion section above, it has updated the AFM phrase to read “If the intermittent cabin altitude/configuration warning horn sounds in flight: * * *” We have approved this new phrase in the AD as acceptable for compliance with the requirements of paragraph (a) of ADs 2003-14-08 and 2003-03-15 R1.

FAA's Determination and Requirements of This AD

The unsafe condition described previously is likely to exist or develop on other airplanes of the same type design. For this reason, we are issuing this AD to prevent failure of the airplane to pressurize and subsequent 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 body) and consequent loss of airplane control. This AD requires revising the airplane flight manual (AFM) to advise the flightcrew of improved procedures for pre-flight setup of the cabin pressurization system, as well as improved procedures for interpreting and responding to the cabin altitude/configuration warning horn.

Interim Action

Revisions to the Emergency or Non-Normal Procedures sections of the AFM are considered to be interim action. The manufacturer has advised that it currently is developing a design change in the cabin altitude warning system that will address the unsafe condition addressed by this AD. Once this design change is developed, approved, and available, the FAA may consider additional rulemaking.

FAA's Determination of the Effective Date

Since an unsafe condition exists that requires the immediate adoption of this AD, we have found that notice and opportunity for public comment before issuing this AD are impracticable, and that good cause exists to make this AD effective in less than 30 days.

Comments Invited

This AD is a final rule that involves requirements that affect flight safety and was not preceded by notice and an opportunity for public comment; however, we invite you to submit any relevant written data, views, or arguments regarding this AD. Send your comments to an address listed in the ADDRESSES section. Include “Docket No. FAA-2006-25102; Directorate Identifier 2006-NM-117-AD” at the beginning of your comments. We specifically invite comments on the overall regulatory, economic, environmental, and energy aspects of the AD that might suggest a need to modify it.

We will post all comments we receive, without change, to http://dms.dot.gov,, including any personal information you provide. We will also post a report summarizing each substantive verbal contact with FAA personnel concerning this AD. Using the search function of that Web site, anyone can find and read the comments in any of our dockets, including the name of the individual who sent the comment (or signed the comment on behalf of an association, business, labor union, etc.). You may review the DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (65 FR 19477-78), or you may visit http://dms.dot.gov.

Examining the Docket

You may examine the AD docket on the Internet at http://dms.dot.gov,, or in person at the Docket Management Facility office between 9 a.m. and 5 p.m., Monday through Friday, except Federal holidays. The Docket Management Facility office (telephone [phone]) is located on the plaza level of the Nassif Building at the DOT street address stated in the ADDRESSES section. Comments will be available in the AD docket shortly after the Docket Management System receives them.

Authority for This Rulemaking

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.

Regulatory Findings

We have determined that this AD will not have federalism implications under Executive Order 13132. This AD 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.

For the reasons discussed above, I certify that the regulation:

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); and

3. 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.

We prepared a regulatory evaluation of the estimated costs to comply with this AD and placed it in the AD docket. See the ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

• Air transportation
• Aircraft
• Aviation safety
• Safety

Adoption of the Amendment

Accordingly, under the authority delegated to me by the Administrator, the FAA amends 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.

§ 39.13

[Amended]

2. The Federal Aviation Administration (FAA) amends § 39.13 by adding the following new airworthiness directive (AD):

2006-13-13 Boeing: Amendment 39-14666. Docket No. FAA-2006-25102; Directorate Identifier 2006-NM-117-AD.

Effective Date

(a) This AD becomes effective July 7, 2006.

Affected ADs

(b) This AD is related to paragraph (a) of AD 2003-03-15 R1, amendment 39-13366, and paragraph (a) of AD 2003-14-08, amendment 39-13227. This AD does not supersede the requirements of AD 2003-03-15 R1 or AD 2003-14-08.

Applicability

(c) This AD applies to all Boeing Model 737-100, -200, -200C, -300, -400, -500, -600, -700, -700C, -800 and -900 series airplanes, certificated in any category.

Unsafe Condition

(d) This AD results from reports that airplanes have failed to pressurize, and that the flightcrews failed to react properly to the cabin altitude warning horn. We are issuing this AD to prevent failure of the airplane to pressurize and subsequent 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 body) and consequent loss of airplane control.

Compliance

(e) You are responsible for having the actions required by this AD performed within the compliance times specified, unless the actions have already been done.

Revising the Airplane Flight Manuals (AFMs)

(f) Within 60 days after the effective date of this AD, revise the Cabin Pressurization procedures in the Normal Procedures section of the AFMs for Model 737-100, -200, -200C, -300, -400, -500, -600, -700, -700C, -800, and -900 series airplanes to include the following procedure:

“For normal operations, the pressurization mode selector should be in AUTO prior to takeoff.”

(g) Within 60 days after the effective date of this AD, revise the Emergency Procedures section of the AFMs for Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, or the Non-Normal Procedures section of the AFMs for Model 737-600, -700, -700C, -800, and -900 series airplanes, as applicable, to include the following procedure:

“Warning Horn—Cabin Altitude or Configuration Recall

Condition: An intermittent or steady warning horn sounds:

• In flight an intermittent horn indicates the cabin altitude is at or above 10,000 feet
• On the ground an intermittent horn indicates an improper takeoff configuration when advancing thrust levers to takeoff thrust
• In flight a steady horn indicates an improper landing configuration.

If an intermittent horn sounds in flight:

Oxygen Masks and Regulators	on, 100%
Crew Communications	Establish
Do the Cabin Altitude Warning or Rapid Depressurization checklist.

If an intermittent horn sounds on the ground: Assure proper airplane takeoff configuration.

If a steady horn sounds in flight: Assure proper airplane landing configuration.”

Optional Action for Certain Requirements of AD 2003-03-15 R1 and AD 2003-14-08

(h) For Model 737-100, -200, -200C, -300, -400, and -500 series airplanes: Using the phrase, “If the intermittent cabin altitude/configuration warning horn sounds in flight:” in place of the phrase, “If the cabin altitude warning horn sounds:”, in the revisions to the “Cabin Altitude Warning or Rapid Depressurization” procedure specified in Figures 2 and 3 of AD 2003-03-15 R1, is acceptable for compliance with the requirements of paragraph (a) of AD 2003-03-15 R1. All other requirements of AD 2003-03-15 R1 remain unchanged.

(i) For Model 737-600, -700, -700C, -800, and -900 series airplanes: Using the phrase, “If the intermittent cabin altitude/configuration warning horn sounds in flight:” in place of the phrase, “Condition: The cabin altitude warning horn sounds:”, in the revisions to the “Cabin Altitude Warning or Rapid Depressurization” procedure specified in Figure 1 of AD 2003-14-08, is acceptable for compliance with the requirements of paragraph (a) of AD 2003-14-08. All other requirements of AD 2003-14-08 remain unchanged.

Alternative Method To Revising the AFM

(j) The AFM revisions specified in paragraphs (f) and (g) of this AD may be done by inserting a copy of this AD into the AFM.

(k) When statements identical to those specified in paragraphs (f) and (g) of this AD have been included in general revisions of the AFM, then the general revision(s) may be inserted into the AFM, and the copy of the AD may be removed from the applicable revised sections of the AFM.

Alternative Methods of Compliance (AMOCs)

(l)(1) The Manager, Seattle Aircraft Certification Office (ACO), FAA, has the authority to approve AMOCs for this AD, if requested in accordance with the procedures found in 14 CFR 39.19.

(2) Before using any AMOC approved in accordance with § 39.19 on any airplane to which the AMOC applies, notify the appropriate principal inspector in the FAA Flight Standards Certificate Holding District Office.

Material Incorporated by Reference

(m) None.

Issued in Renton, Washington, on June 15, 2006.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.