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The Boeing Company 

P.O. Box 3707 

Seattle, WA 98124-2207 

: ARTMENTOF 

::-i^PORWION 

^ , ^ ,^^„, , ^^'OPERATIGNS 

September 19,2011 

RA-11-05061 

^!! ';:P 2! P !2:01 

U.S. Department of Transportation 

Docket Operations 

Docket FAA-2008-1249 

West Building Ground Floor, Room W12-140 

1200 New Jersey Avenue, SE 

Washington D.C. 20590 

Subject: Clarification of Exemption 9791C from 14 CFR §25.853(a) 

Reference: (a) FAA Exemption Number 9791C, Regulatory Docket No. 

FAA-2008-1249 

Dear Sir or Madam: 

The Boeing Company respectfully requests a clarification of the Reference (a) time limited 

exemption from the requirements of 14 CFR §25.853(a). The clarification addresses modification 

kits and spare parts certified prior to the expiration of the referenced time limited exemption on 

November 28, 2011 but which are subsequently shipped to or installed by airlines after November 

28,2011. 

The Reference (a) time limited exemption states the following: 

"The Boeing Company is thereby granted an exemption from tiie flammability testing 

requirements of 14 CFR 25.853(a), to the extent required to permit type ceiiification of 

the Boeing airplane types note in the referenced petition until November 28, 2010. The 

following limitations apply to this exemption: 

This exemption is limited to the Boeing and former McDonnell Douglas airplane 

models noted in the petition and applies to the following adhesives: 

• BMS 5-92 Type I (3M Scotchweld EC2216B/A) 

• BMS 5-92 Type V (3M Scotchweld EC2615B/A) 

• JD Lincoln L-301 

• JD Lincoln L-301 R 

• BMS 5-107 (Araldite 420 A/B) 

• Lord 270 A/B 

• 3M Scotchweld 9323-2 A/B 

• Aerobond 1507 /^B 

• Aerobond 1508 A/B (fire retardant) 

In addition, this grant is extended to those STC holders and applicant that modify or have 

modified the airplanes listed above during the period of exemption." 

The date was later extended to November 28, 2011. 

The current position in Reference (a) primarily addressed new aircraft delivered from the Boeing 

Company and Supplemental Type Certificates to the airplane listed in the reference time limited 

exemption. Per that agreement, The Boeing Company has ensured that the subject ditch and pot 

joints that are part of the Type Design of any aircraft delivered after November 28, 2011 are 

shown compliant to 14CFR 25.853(a). The Boeing Company has also ensured that any ditch and 
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Letter RA-11-05061 

Page 2 

pot joints involved in post-delivery changes to Type Design that are certified after November 28, 

2011 are also shown compliant to 14CFR 25.853(a). 

However, in discussions with the FAA, we have discovered that reference A did not clearly define 

expectations for articles in the Type Design which are not part of new deliveries or new 

modifications. The Boeing Company had assumed that these articles would not require reapproval to the new means of compliance, because there is no certification activity associated 

with them (e.g. no certification projects, findings of compliance or statements of compliance are 

currently associated with them). FAA specialists have asked whether this interpretation is 

correct, or whether the ref A exemption would require an assessment of all previously approved 

Type Design, regardless of the date of approval (i.e. potentially all designs that include ditch and 

pot joints, whether currently manufactured or modified, or not). The Boeing Company is 

requesting that Reference (a) be clarified to include allowances for modification kits and spare 

parts that have been certified prior to expiration of this time limited exemption. Boeing is 

requesting that following three proposals be consider in the amendment to Reference (a). 

1. Modification kits and spare parts with ditch and pot joint construction on projects that 

have been certified prior to the end of the Reference (a) Time Limited Exemption period 

do not need to re-substantiated for compliance after the exemption period has concluded. 

In addition, the follow-on incorporation of modification kits and spare parts will not require 

a new showing of compliance unless they have changed. 

Example: A modification project may involve several airplanes being modified over a 

period of time using the same design. If the engineering for such a project is completed 

and the project is closed before the end of the Time Limited Exemption period and one or 

more airplanes complete modification before the end of the TLE period, but one or more 

are modified after the TLE expires, those modified after the TLE expires would not 

require any additional certification activity. 

2. Parts with ditch and pot joint constructions delivered on an aircraft certified prior to the 

end of the time limited exemption period do not need to be substantiated by way of a new 

finding of compliance once the exemption period has expired. 

Example: Spare parts require no additional certification activities providing they remain 

unchanged after the expiration of the time limited exemption. 

3. Previously certified parts that have been changed, but do not affect ditch and point joints, 

do not require a new finding of compliance for the ditch and point joints not impacted by 

the change. 

Example: A modification project may affect an assembly that contains ditch and pot 

joints, but the changes made do not affect the ditch and pot joints. In such a case no 

showing of compliance specific to the ditch and pot joints is required. For example, a 

placard may be added to the exterior wall of a closet that included a ditch and pot joint. 

As long as the change does not affect the joint, our change-based certification process 

would not require a new assessment of the joint. 

The rationale for requesting this amendment is to ensure that the modification kits and spare 

parts can still be provided to the airline industry in a timely and efficient manner. Resubstantiation and re-certification of previously approved modification kits and spare parts drives 

additional work statement and cost to Boeing, the FAA, the airline customer, and the aircraft 

industry a whole. In addition, these ditch and pot construction, while not shown compliant to 14 

CFR 25.853(a), do not present any additional safety concern. Finally as new designs are 

developed, these future ditch and pot joint designs will, over a relatively short period time, begin 

to replace the designs that are being addressed by this exemption. 
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Letter RA-11-05061 

Page 3 

Application after the Exemption Period 

Boeing plans to apply the compliance criteria that will be outlined in the FAA's final policy on new 

findings of compliance for ditch and pot joints when the exemption expires. A new finding of 

compliance would be required for a ditch and pot joint when the joint is changed or if the panel 

design is substantially new. Previously certified panels with changes that do not involve these 

joint constructions will be considered follow-on constructions for this feature, without the need for 

a new finding of compliance. 

Statement of No Adverse Effect to Safety 

For the same reasons provided in our original petition, which were accepted by the FAA in 

granting of Exemption 9791B, amending Exemption 9791C to include allowances for modification 

kits and spare parts will not adversely affect aviation safety, 

Statement of Public interest 

For the same reasons provided in our original petition, which were accepted by the FAA in 

granting of Exemption 9791B, amending Exemption 9791C to include allowances for modification 

kits and spare parts is in the public interest. 

As we had previously requested in our original petition, in accordance with §11.81 (h). The 

Boeing Company also requests the privileges of the requested application of the guidance for 

modification kits and spare parts be extended outside of the United States. These privileges are 

necessary for operations based within foreign countries having bilateral agreements with the 

United States accepting the FAA's 14 CFR part 25 as their airworthiness standards for transport 

category aircraft. 

A response to this petition for extension is requested by September 8, 2011, to support the 

development of year-end deliveries. 

Your timely cooperation in these matters is greatly appreciated. 

Sincerely, 

(AA-K^ 

Douglas Lane 

Director, Regulatory Administration 

Cc: Mr. AN Bahrami 

Mr. Angelos Xidias 

Mr. Mike Kaszycki 

Mr. Bob Breneman 

Federal Aviation Administration 

Transport Airplane Directorate 

1601 Lind Avenue S.W. 

Ronton, WA 98055-4056