# Presentation: 816082

## Operator Requirements for Incorporation of Fuel Tank Flammability Reduction Requirements 

- FAA National Headquarters, Washington, DC

**Operator Requirements for Incorporation of Fuel Tank Flammability Reduction Requirements **

## This familiarization briefing is intended to provide an overview of the operator's requirements.

An Advisory Circular (AC) titled “Operator Requirements for Incorporation of  Fuel Tank Flammability Reduction Requirements” is currently being drafted by the FAA.

The proposed release date for this AC is late October 2008.

Operators are encouraged to refer to this AC as an aid in determining and understanding the multiple facets of this new rule package. 

- An Advisory Circular (AC) titled “Operator Requirements for Incorporation of  Fuel Tank Flammability Reduction Requirements” is currently being drafted by the FAA.
- The proposed release date for this AC is late October 2008.
- Operators are encouraged to refer to this AC as an aid in determining and understanding the multiple facets of this new rule package.

## The Fuel Tank Flammability Reduction (FTFR) rule contains multiple operator requirements:

- Operators of certain US registered airplanes must:
- Install retroactively a Flammability Reduction Means (FRM) such as a nitrogen inerting system.
-  				or
- Install retroactively an Ignition Mitigation Means (IMM) such as polyurethane foam.
- Incorporate Instructions for Continued Airworthiness (ICA) for those systems for newly produced airplanes and retrofitted airplanes.
- Perform a Flammability Exposure Analysis and Impact Assessment for Auxiliary Fuel Tanks.
- Develop and incorporate Flammability Impact Mitigation Means (FIMM) design changes and ICA for Auxiliary  Fuel Tanks.

## New Production Airplanes – FRM/IMM Installation

	Operators who take delivery of newly produced airplanes that have either Flammability Reduction Means (FRM) or Ignition Mitigation Means (IMM) installed must incorporate the related FAA Oversight Office approved Instructions for Continued Airworthiness (ICA) into their maintenance program.  These approved ICA are Airworthiness Limitations Items (ALI) located in the respective manufacturer’s ALS document. These ALI consist of mandatory repetitive maintenance / inspection tasks at specific intervals, as well as Critical Design Configuration Control Limitations (CDCCL) items. 

- 	Operators who take delivery of newly produced airplanes that have either Flammability Reduction Means (FRM) or Ignition Mitigation Means (IMM) installed must incorporate the related FAA Oversight Office approved Instructions for Continued Airworthiness (ICA) into their maintenance program.  These approved ICA are Airworthiness Limitations Items (ALI) located in the respective manufacturer’s ALS document. These ALI consist of mandatory repetitive maintenance / inspection tasks at specific intervals, as well as Critical Design Configuration Control Limitations (CDCCL) items.

**§****121.1117, 125.509, and 129.117 ****Operator Requirements **

## FRM Example

- 	The Boeing Airplane Company is currently installing a FRM system into their newly produced B-737 airplane models.  This system is a nitrogen generation system referred to as an “Inert Gas System” (ATA Chapter 47).  All of the ICA for the maintenance and inspection of this system are located in their respective Maintenance Planning Document (MPD) section 9 which is their FAA Approved ALS.  It is the operator’s responsibility to incorporate all these ALI into their respective maintenance program.  In order to accomplish this task the operator must submit their proposed FRM/IMM program to the Principal Maintenance Inspector who will compare the program to the respective airplane FRM/IMM ALS requirements and approve implementation using operations specifications (OpSpecs) from the automated Operations Safety System (OPSS) database.

##      Existing all cargo configured airplanes are excluded from the Part 26 FRM/IMM retrofit requirements.   However, newly manufactured Boeing and Airbus airplanes, both passenger and cargo, that have an original airworthiness certificate issued after September 20, 2010, that are added to an operator’s fleet must have the center wing tank FRM/IMM installed to meet the requirements of section 26.33.  These airplanes are not included when determining compliance with the operators 50% interim retrofit requirement. 

	Additionally, it should be noted that in the event a registered passenger use airplane that has had FRM/IMM retroactively installed is converted to a cargo use airplane, the FRM/IMM system must remain operational. 

- 	Additionally, it should be noted that in the event a registered passenger use airplane that has had FRM/IMM retroactively installed is converted to a cargo use airplane, the FRM/IMM system must remain operational.

**Operator Requirements cont’d**

## Operator Requirements cont’d

- 	Operators of passenger airplanes, if FRM or IMM are required by sections 26.33, 26.35 or 26.37 and were issued an airworthiness certificate on or after January 1, 1992, are required to incorporate FRM or IMM into those airplanes within 9 years after the effective date of the rule.  The incorporation of the modifications to the operator’s fleet is intended to be phased into their fleets over a 9 year period such that all airplanes in an operator’s fleet will meet the new fuel tank safety standards.  To achieve this result an interim compliance date is included in the operational rules.  Fifty percent of the airplanes must be retrofitted within 6 years of the effective date of the rule. Once FRM/IMM is installed into a particular airplane, it must remain installed, and be operational, except in accordance with the applicable Master Minimum Equipment List (MMEL) conditions and limitations.
- 	In addition to incorporating the FRM/IMM system into the airplanes in accordance with the time line, the operators are responsible upon commencement of the retrofit to incorporate into their maintenance program all applicable FAA Oversight Office approved Airworthiness Limitation Items (ALI) after being submitted to the Principal Maintenance Inspector (PMI) for review and approval via operational specifications.

**Operator Requirements cont’d**

## Operator Requirements cont’d

- 	The operational rules do not require modification of older airplanes certificated prior to January 1, 1992 unless they are operated in passenger service beyond 2017. The need to incorporate FRM or IMM into specific airplanes within an operator’s fleet depends upon the date of issuance of the original certificate of airworthiness.  Operators may determine if individual airplanes in their fleet received an original certificate of airworthiness on or after January 1, 1992, by checking with the manufacturer, or via the web at: _[http://registry.faa.gov/aircraftinquiry/](http://registry.faa.gov/aircraftinquiry/)__.  At the web site, simply enter the airplane N number, or serial number, and refer to the block labeled “A/W Date”. _

**Operator Requirements cont’d**

## Slide 9

## Ground Conditioned Air Program – Option 

- Part 121 and 129 operators may extend compliance times by one year, if they adopt a FAA approved “Ground Conditioned Air Program” authorized by a new Operations Specification.
- The program would require the operators detail such a program in their manual(s) and be committed to adhering to the program, or risk losing the extension privileges of the program.
- The program would require ground conditioned air be used on the applicable airplanes where actual gate times exceed 30 minutes where ground conditioned air is available, and the ambient temperature exceeds 60 degrees F.
- Note: This program was not conceived by the FAA. It was adopted from a Boeing Service Letter suggested program instituted in May 2000.

## Slide 11

## 
	Fuel tank system airworthiness limitations include mandatory maintenance and inspection actions to ensure that unsafe conditions identified by the DAH do not occur or are not introduced into the affected fuel tank that could ultimately affect the fuel tank system. These ALI are developed IAW part 25, § 25.981, amendment 25-102, for designs developed after June 6, 2001. These ALI are required to be established to prevent development of fuel tank flammability increases above the required limits as a result of configuration changes, repairs, alterations, or deficiencies in the maintenance program throughout the operational life of the airplane. A fuel tank system ALI related to fuel tank flammability reduction may be a specific repetitive inspection or maintenance action, or a Critical Design Configuration Control Limitation (CDCCL).

- 	Fuel tank system airworthiness limitations include mandatory maintenance and inspection actions to ensure that unsafe conditions identified by the DAH do not occur or are not introduced into the affected fuel tank that could ultimately affect the fuel tank system. These ALI are developed IAW part 25, § 25.981, amendment 25-102, for designs developed after June 6, 2001. These ALI are required to be established to prevent development of fuel tank flammability increases above the required limits as a result of configuration changes, repairs, alterations, or deficiencies in the maintenance program throughout the operational life of the airplane. A fuel tank system ALI related to fuel tank flammability reduction may be a specific repetitive inspection or maintenance action, or a Critical Design Configuration Control Limitation (CDCCL).

**Airworthiness Limitations**

## Critical Design Configuration Control Limitation (CDCCL)

- A CDCCL is any information necessary to maintain those design features that have been defined in the original type design as needed to preclude development of ignition sources and provide a means to minimize the development of flammable vapors.  The purpose of the CDCCL in the context of the FTFR rule is to provide instructions to retain the critical flammability reduction feature during configuration change that may be caused by alterations, repairs, or maintenance actions.
- A critical flammability reduction feature may exist in the fuel system and its related installation that if a failure happens could interact with the fuel system resulting in an unsafe condition without this limitation. Therefore, repetitive action Airworthiness Limitations, including CDCCLs, must be included in the manufacturer’s Airworthiness Limitations section (ALS) and subsequently be incorporated into the operator’s maintenance program.
-  CDCCL are the primary means of managing and controlling the configuration of the ignition source prevention features and the designed means to reduce flammable vapors in the airplane’s fuel tank system.
- CDCCLs are not inspections, maintenance actions, or life limited items and therefore do not have a specific task or interval associated with them. They are simply stated, specific instructions that are designed to ensure whenever maintenance actions, repairs or design changes occur the critical configuration is not compromised.

## Current Example of B-737-600/700/800/900 Nitrogen Generation System ALI

| AWL Number  | Task | Interval | Applicability | Description |
| --- | --- | --- | --- | --- |
| 47-AWL- 03 | ALI | 1200 FH | L/N 1820 and 1831 | Nitrogen Generation System –Functional Check Performance Inspection
Concern: Latent failure of the Hollow Fiber Membranes that make up the Air Separation Modules (ASMs) will reduce the percentage of nitrogen enriched air entering the center wing tank.  |

## Current Example of B-737-600/700/800/900 Nitrogen Generation System CDCCL

| AWL Number | Task | Interval | Applicability | Description |
| --- | --- | --- | --- | --- |
| 47‐AWL- 01 | CDCCL | N/A | L/N 1820,1831,2517, 2620 and on.  | Lightning Protection-FRS NEA Distribution Line Fuel Tank Penetration. Concern: Potential for arcing, sparking or filament heating inside the tank at the interface between the bulkhead fitting and the spar during a lightning strike event.
The following must be maintained per AMM 47-21-07 if the bulkhead fitting or attached tubing are removed and replaced: 1. Verify electrical fay surface bond between the bulkhead fitting and the front spar structure inside the tank must be 0.0005 ohms or less, 2. Install full-bodied fillet seal encapsulating the bulkhead fitting to the tank wall interface inside the tank, 3. Install full-bodied fillet seal encapsulating the first coupling interface inside the tank, and 4. Verify electrical bond from structure to first tube mating with the bulkhead fitting is 0.010 ohms or less. |

**Current Example of B-737-600/700/800/900 Nitrogen Generation System CDCCL**

## STC AND FIELD APPROVED AUXILIARY FUEL TANKS

- STC holders are the Design Approval Holder (DAH) for several existing fuel tanks that are   presently installed in transport category airplanes.  At present, the FAA is not aware of any specific operators that have field approved auxiliary fuel tanks in their airplanes, however if there are such installations, those operators are the DAH for those fuel tank installations.  As such, these DAHs are required to comply with certain provisions of § 26.35. There is no requirement to install an FRM or IMM in these particular tanks, however these DAHs must conduct a "“Flammability Exposure Analysis” and an “Impact Assessment.”  Depending on the outcome of the Impact Assessment, certain of these DAHs may be required to develop design changes and service instructions if their designs compromise CDCCLs developed by the type certificate holders.  If design changes are required they must also perform a flammability exposure analysis of the fuel tank after incorporation of these design changes.  These requirements are discussed further on the following slides.

## Flammability Exposure Analysis

- 	Section 26.35(b(i) requires the DAHs perform a flammability analysis in accordance with Appendix N to part 25, amendment 25-125, of any of their auxiliary fuel tanks that are eligible for installation in any transport category airplane that is subject to § 26.33(a).  As the DAH, they are required to submit their analysis for approval to the cognizant FAA Oversight Office within 12 months after September 19, 2008.

## Impact Assessment

- 	If any of these auxiliary fuel tanks are eligible for installation in any airplanes listed in Table 1 of § 26.35 (also listed in Table 1 of the AC), the DAH is required by § 26.35(c) to perform an impact assessment.  The impact assessment is to identify any features of their design change that compromise any CDCCL for any airplane on which the fuel tank is eligible for installation.  This requirement is necessary to ensure the auxiliary fuel tank does not adversely impact any FRM or IMM developed for those airplanes.
- 	For example, if fuel was transferred from an auxiliary fuel tank to a Normally Emptied center wing tank (CWT) using air pressure in the auxiliary fuel tank, air could be introduced into the CWT.  If that CWT was required by § 26.33 to incorporate an FRM, and the FRM design lowered the oxygen concentration of the fuel tank ullage, the air flow from the auxiliary fuel tank could cause the oxygen concentration to increase above that required by the FRM design.  This auxiliary fuel tank design would then compromise the CDCCL required by the FRM installation.

## Flammability Impact Mitigation Means (FIMM)

**	****Design Changes and Service Instructions:  Section 26.35(d) requires these DAH to develop design changes and service instructions if the impact assessment identified any features of the auxiliary fuel tank installation that compromised any CDCCLs.  The design changes are referred to as Flammability Impact Mitigation Means (FIMM)   The FIMM are required to bring the auxiliary fuel tank installation into compliance with the airplane CDCCL.  The DAH is also required by this § 26.35(d) to perform a flammability assessment of the auxiliary fuel tank as modified by the FIMM.  The DAH is required to submit the FIMM design changes and service instructions to the FAA Oversight Office for approval.  Section 26.35(e) requires the DAH submit the design changes and service information to the FAA Oversight Office by September 19, 2012. **
**	****In accordance with §**** ****121.1117(d)(1) operators are responsible to install any necessary FIMM and incorporate the associated ICA into their maintenance program in accordance with the same retrofit schedule used for their FRM or IMM installation.**

##  Conducting a Flammability Analysis and Impact Assessment for an aux tank if an STC holder does not provide the required analysis

- 	The FAA recognizes that there may be some occasions where the DAH is unwilling or unable to comply with the Part 26 regulations.  There may also be cases where the DAH no longer exists.  Under these circumstances the operator is still obligated to comply with the operational rules.  However, the FAA realizes that those occasions may significantly complicate the operator’s effort to show compliance with the operational rules.  The FAA recommends the affected operators contact their DAH’s early in the compliance process period to ensure their intent to comply.  Operators should also familiarize themselves with the regulations and the associated guidance information contained in the relevant ACs and policy so they can determine the best way to obtain necessary data and documents in the event a DAH is unwilling or unable to support the compliance activity.  Affected operators are also encouraged to collaborate with other operators who may also be impacted by lack of support on the means for compliance.
- 	Some STC holders have surrendered their STCs rather than comply with the DAH requirements.  In this case the data from the STC remains the property of the STC holder even though the STC has been surrendered.  If an operator desires the data from the STC holder they would need to make financial arrangements with the owner of the STC for access to the data.

## STC and  Field Approved Auxiliary Fuel Tanks

**	****In the event an operator chooses to deactivate, or remove a STC, or field- approved installed auxiliary fuel tank rather than comply with the Part 26 requirements, such action can only be accomplished using FAA approved data. **

## TC and Amended TC Auxiliary Fuel Tanks

**	****In the event that a TC holder such as Boeing or Airbus installs an auxiliary fuel tank as part of the type design they are required to comply with the provisions of §26.33.  This is because the requirements of § 26.33 apply to all fuel tanks defined in the type design, as well as all design variations approved under the type certificate (e.g., amended type certificate) for all those airplanes affected by § 26.33.  Therefore, there could be a requirement to install an FRM or IMM in these particular tanks. Specifically, these TC holders are required to do a Flammability Exposure Analysis and determine if the subject tanks are highly flammable.  If highly flammable the TC holder would be responsible for design modifications to install FRM or IMM. **

## Operator’s FTFR Approval Under §§ 121.1117, 125.509 And 129.117 

**	****Parts 121, 125, and 129 operators will be issued newly developed OpSpecs from the OPSS data‐base to implement FTS requirements. The operators must first submit their proposed FTFR program to their Principal Maintenance Inspector (PMI) who will compare the operator’s proposed program to the TC /STC holder’s Airworthiness Limitations ICA, and approve operator incorporation with the new OpSpecs. **
**	****Operators must submit the following to the PMI, as applicable:**
**Ground Conditioned Air Program**
**Airworthiness Limitation Section FRM/IMM ICA for newly produced airplanes and retrofitted airplanes**
**Auxiliary Fuel Tank Flammability Impact Means (FIMM) ICA**

## To avoid interruption and achieve timely retrofit compliance, operators should consider providing their FAA Flight Standards Certificate Holding District Office (CHDO) a matrix that contains by N registration number and fleet type, a listing of what airplanes in their fleet require retrofit installation of FRM or IMM.  

Additionally, the operator should consider providing a matrix that contains by N registration number and fleet type, a listing of what airplanes have auxiliary fuel tanks installed of which the various FTFR requirements may be required.

An agreement between the operator and CHDO should be made as to how ongoing compliance with the FTFR rules will be communicated and tracked. 

- Additionally, the operator should consider providing a matrix that contains by N registration number and fleet type, a listing of what airplanes have auxiliary fuel tanks installed of which the various FTFR requirements may be required.
- An agreement between the operator and CHDO should be made as to how ongoing compliance with the FTFR rules will be communicated and tracked.

**Operator  Compliance Plan**

## FTFR Awareness Training

- 	There is no regulatory requirement mandating specific training however the new rule has introduced new requirements and new aircraft systems that affect design approval holders and operators.

- 	To fully realize the objectives of the FTFR rule goal, operators need to address their current philosophical approach and knowledge level pertinent to installing, maintaining, inspecting, and altering these systems.  This approach has begun at the airplane manufacturers with maintenance program enhancements that address fuel tank flammability reduction. It is incumbent that the operators include these TC and STC holder fuel tank system maintenance program enhancements into their respective programs. Furthermore, they should commit to training their maintenance and inspection work force to understand the new flammability reduction systems, and in particular to gain insight as to the additional cautions and procedures regarding fuel tank entry with a nitrogen generation system installed.

## Questions