AmericanAirlines® 


MAINTENANCE & ENGINEERING CENTER 

February 24, 2011 

U. S. Department of Transportation 

Docket Operations 

West Building Ground Floor, Room W12-140 

1200 New Jersey Avenue, SE. 

Washington DC, 20590 

! 

Subject: Request for Exemption to Sections 'of 14 CFR Part 121.344: 

American Airlines, Inc. would like to petition the Federal Aviation Administration for a timelimited exemption of 18 months from December 6, 2010, to 14 CFR 121.344 to continue 14 CFR 

121 operations of two additional 737-823 series aircraft. The expected deliveries of these 

aircraft are in May and June of 2011 , which will occur prior to Boeing's certification of the 

corrected Flight Data Recorder System data frame software. This exemption request involves 

the same 737-7 data frame for which American was granted an exemption of the rudder pedal 

input force parameter and left elevator surface position parameter (Reference Exemption No. 

10173A. Regulatory Docket No. FAA-201 0-1178 dated December 21, 2010). 

Applicable Sections: 

14 CFR 121.344 (f) states "For all turbine-engine-powered transport category airplanes that are 

manufactured after August 19, 2002 - (1) The parameters listed in paragraph (a) (1) through 

(88) of this section must be recorded within the rariges, accuracies, resolutions, and recording 

intervals specified in Appendix M of this part. (2) In addition to the requirements of paragraphs 

(f)(1) of this section, all Boeing 737 model airplanes must also comply with the requirements of 

paragraph (n) of this section." 

14 CFR 121 .344 (n) states "In addition to all other applicable requirements of this section, all 

Boeing 737 model airplanes manufactured after August 18, 2000 must record the parameters 

listed in paragraphs (a)(88) through (a)(91) of this section within the ranges, accuracies, 

resolutions, and recording intervals specified in Appendix M to this part. Compliance with this 

paragraph is required no later than February 2, 2011. " 

14 CFR 121 .344 Appendix M (Note 18) states "For all aircraft manufactured on or after 

December 6, 2010, the seconds per sampling interval is O. 125. Each input must be recorded at 

this rate. Alternately sampling inputs (interleaving) to meet this sampling interval is prohibited." 

Extent of Relief 

This time-limited exemption would allow for the continued domestic and international operations 

of the following American Airlines operated B737 -823 series aircraft (see Table 1) for 18 months 

after December 6, 2010, without the fully compliant recording interval of the rudder pedal force 

parameter and left elevator surface position paraf!1eter (see Table 2): 

Make I Model Serial # Line # Registration # 

Boeing / 737-823 40762 3634 N867NN 

Boeing I 737-823 40763 3668 N868NN 

MD__ P.O. BOX 582809, TULSA, OKLAHOMA 741 59-2809, CABLE ADDRESS AMAIR 
American Airlines - 737NG Exemption Requesl 

Table 2 

121.344 (f) Appendix M 

Parameter # Requirement Input to DFDAU 

15 Pitch Control Left Elevator Position Data 

Surface Position (1 sample of the 8 Hz set 

every 5 seconds) 

88 Rudder Pedal Input Force Rudder Pedal Force Data 

(1 sample of the 8 Hz set 

every 5 seconds) 

Reason for relief 

This exemption is necessitated by the Aircraft Manufacturer (Boeing) and the Digital Flight Data 

Acquisition Unit (DFDAU) system / software supplier's (Teledyne) need to develop, validate, and 

integrate the enhanced system software into the aircraft type design. This enhanced software 

will provide for the DFDAU recording of all regulatory required parameters and allow American 

Airlines time to install the software without significantly affecting flight operations. 

Background 

Summary: 

A 737NG Flight Data Recorder System (FDRS) anomaly was discovered during Boeing flight 

line airplane operations. It was later found that the left elevator position parameter and the 

rudder pedal force parameter were not being acquired completely, hence recorded properly. 

This FDRS configuration includes a Teledyne Digital Flight Data Acquisition Unit (DFDAU) with 

the 737-7 data frame enabled. The data frame is a 512 words per second data frame that was 

certified in April of 2010 to meet the latest FAA regulations (§ 121.344 (f) Appendix M), which 

was effective starting December 6, 2010. The following describes the anomaly and discusses 

Boeing's plan to correct the discrepancy. 

Discussion: 

The root cause of this anomaly is found in a DFDAU software acquisition timing error. 

Periodically, in a given parameter acquisition cycle, the DFDAU is requesting the acquisition of 

more parameter data than it has time to complete in that acquisition cycle. Because parameter 

acquisition does not have time to complete the previous valid sample is used in the recording 

rather than the desired current sample. 

The DFDAU software is on-wing loadable and Teledyne has informed Boeing that this anomaly 

can be fixed with a minor software revision resulting in new software part numbers. 

Plan to Correct Anomaly: 

Boeing has verbally notified the FAA and is in the process of filing a "Report of Noncompliance 

with Part 25 Airworthiness Regulations" with the FAA stating that the anomaly does not 

represent a safety issue for continued operation. 

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American Airlines - 737NG Exemption Request 

Boeing has a pending contract in-work with and its acceptance the plan is 

certify the new DFDAU software in ...... ""'01\/ 5 months. of certification is 

contingent on what is found during which may cause the schedule to move either left or the 

right In any case, Boeing is working to certification of corrected 

software. 

Upon receipt of the Boeing Bulletin American Airlines will install 

this software within 90 days, terminating the exemption. 

Public Interest 

The granting of this exemption would be in the public by allowing American Airlines to 

continue providing service to domestic and international utilizing the B737-823 

aircraft listed in Table 1. 

Failure to grant this exemption may require American Airlines to cancel flights and disrupt 

schedules causing significant financial loss as well as inconvenience and potential losttime cost to the traveling public. 

Affect on the Level of Safety 

American Airlines understands that the flight recorder an impact on the 

operation of aircraft, but they do provide a means based on availability 

after an accident or incident. American believes that infrequent loss of the rudder 

pedal parameter will not cause significant in a sufficient amount of data 

from this parameter. The availability of the rudder pedal position and rudder parameters will 

the missing data. 

for the Federal Register 

described in 14 11.87, American exemption not be published 

Register and follow with request for comments to ensuing delay of 

ron'rlnn the exemption. 

Airlines is requesting an exemption [from 14 CFR to allow for the 

operation of B737 -823 series aircraft in domestic and international revenue service 

without of all 8 samples of the rudder left elevator position 

This exemption shall allow the Aircraft Manufacturer and the DFDAU System 

Provider (Teledyne) time to develop, validate, and to correct the 

anomaly and allow American Airlines time to install with minimal 

interruption to flight scheduling. 

Additional Information 

verbally notified the FAA and is in the of filing a 

Airworthiness Regulations" with the FAA stating that 

issue for continued operation. 

30f4 
American Airlines - 737NG Exemption Request 

Use of the Exemption outside the United States 

American Airlines would like to utilize the privileges of this exemption outside the United States. 

The primary scheduled operations for this model aircraft in American Airlines fleet includes 

international operations primarily in Mexico, Canada, Central America, South America and the 

Caribbean. 

Your consideration of the foregoing approval of this request is appreciated. If you have any 

questions regarding this request, please feel free to contact this office. 

;J~d)- William M. Cavitt 

Vice President 

Engineering, Performance and Quality Assurance 

On behalf of: American Airlines, Inc. 

Air Carrier Certificate AALA025A 

3900 N Mingo Rd, MD 183 

Tulsa, OK 74116 

Phone: 918-292-2902 

Fax: 918-292-1830 

Email: bill.cavitt@aa.com 

WMC/DZ: bt 

cc: 	 Federal Aviation Administration 

AAL Certificate Management Office 

c/o Mr. William T. Satterfield, PAl 

14800 Trinity Blvd, St. 100 

Fort Worth, Texas 76155 

The Boeing Company 

B. C. Groenewegen, 

Manager, Continued Airworthiness 

Twin Aisle Programs 

P.O. Box 3707 

Seattle WA 98214-2207 

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