477 

Federal Aviation Administration, DOT 

§ 26.33 

(i) Fuel tanks for which the type cer-

tificate holder has notified the FAA 
under paragraph (g) of this section that 
it will provide design changes and serv-
ice instructions for Flammability Re-
duction Means or an Ignition Mitiga-
tion Means (IMM) meeting the require-
ments of paragraph (c) of this section. 

(ii) Fuel tanks substantiated to be 

conventional unheated aluminum wing 
tanks. 

(c) 

Design Changes. 

For fuel tanks 

with a Fleet Average Flammability Ex-
posure exceeding 7 percent, one of the 
following design changes must be 
made. 

(1) 

Flammability Reduction Means 

(FRM). 

A means must be provided to 

reduce the fuel tank flammability. 

(i) Fuel tanks that are designed to be 

Normally Emptied must meet the 
flammability exposure criteria of Ap-
pendix M of part 25 of this chapter if 
any portion of the tank is located with-
in the fuselage contour. 

(ii) For all other fuel tanks, the FRM 

must meet all of the requirements of 
Appendix M of part 25 of this chapter, 
except, instead of complying with para-
graph M25.1 of this appendix, the Fleet 
Average Flammability Exposure may 
not exceed 7 percent. 

(2) 

Ignition Mitigation Means (IMM). 

A 

means must be provided to mitigate 
the effects of an ignition of fuel vapors 
within the fuel tank such that no dam-
age caused by an ignition will prevent 
continued safe flight and landing. 

(d) 

Service Instructions. 

No later than 

December 27, 2010, holders of type cer-
tificates required by paragraph (c) of 
this section to make design changes 
must meet the requirements specified 
in either paragraph (d)(1) or (d)(2) of 
this section. The required service in-
structions must identify each airplane 
subject to the applicability provisions 
of paragraph (a) of this section. 

(1) 

FRM. 

The type certificate holder 

must submit for approval by the re-
sponsible Aircraft Certification Service 
office design changes and service in-
structions for installation of fuel tank 
flammability reduction means (FRM) 
meeting the criteria of paragraph (c) of 
this section. 

(2) 

IMM. 

The type certificate holder 

must submit for approval by the re-
sponsible Aircraft Certification Service 

office design changes and service in-
structions for installation of fuel tank 
IMM that comply with 14 CFR 25.981(c) 
in effect on December 26, 2008. 

(e) 

Instructions for Continued Air-

worthiness (ICA). 

No later than Decem-

ber 27, 2010, holders of type certificates 
required by paragraph (c) of this sec-
tion to make design changes must sub-
mit for approval by the responsible 
Aircraft Certification Service office, 
critical design configuration control 
limitations (CDCCL), inspections, or 
other procedures to prevent increasing 
the flammability exposure of any tanks 
equipped with FRM above that per-
mitted under paragraph (c)(1) of this 
section and to prevent degradation of 
the performance of any IMM provided 
under paragraph (c)(2) of this section. 
These CDCCL, inspections, and proce-
dures must be included in the Air-
worthiness Limitations Section (ALS) 
of the ICA required by 14 CFR 25.1529 or 
paragraph (f) of this section. Unless 
shown to be impracticable, visible 
means to identify critical features of 
the design must be placed in areas of 
the airplane where foreseeable mainte-
nance actions, repairs, or alterations 
may compromise the critical design 
configuration limitations. These visi-
ble means must also be identified as a 
CDCCL. 

(f) 

Airworthiness Limitations. 

Unless 

previously accomplished, no later than 
December 27, 2010, holders of type cer-
tificates affected by this section must 
establish an ALS of the maintenance 
manual or ICA for each airplane con-
figuration evaluated under paragraph 
(b)(1) of this section and submit it to 
the responsible Aircraft Certification 
Service office for approval. The ALS 
must include a section that contains 
the CDCCL, inspections, or other pro-
cedures developed under paragraph (e) 
of this section. 

(g) 

Compliance Plan for Flammability 

Exposure Analysis. 

Within 90 days after 

December 26, 2008, each holder of a type 
certificate required to comply with 
paragraph (b) of this section must sub-
mit to the responsible Aircraft Certifi-
cation Service office a compliance plan 
consisting of the following: 

(1) A proposed project schedule for 

submitting the required analysis, or a 
determination that compliance with 

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