Enclosure to RA-12-04444

Petition for Exemption from 14 CFR 25.981(a )(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126, Code of Federal Regulations

1 Petition for Exemption from 14 CFR 25. 981(a)(3) Amendment 25

- 125 and 14 CFR 25.901(c) Amendment 25-126 pertaining to planned changes for the 767-200, 767-300, 767-300F, 767- 400ER Fuel Quantity Indi cation System (FQIS)

Name and Address of the Petitioner

Douglas Lane, Director, Re gulatory Administration The Boeing Company

PO Box 3707 Seattle, Washington, 98124

Section(s) of the Regulations from which Relief is sought:

14 CFR 25.901(c) at Amendment 25-126 requires:

(c) For each powerplant and auxi liary power unit installation, it must be established that no single failure or malfunction or probable combin ation of failures will jeopardize the safe operation of the airplane except th at the failure of structural el ements need not be considered if the probability of such failure is extremely remote.

14 CFR 25.981(a)(3) at Am endment 25-125 requires:

(a) No ignition source may be present at each poi nt in the fuel tank or fuel tank system where catastrophic failure could occur due to ignition of fuel or va pors. This must be shown by:

(3) Demonstrating that an ignition source could not result from each single failure, from each single failure in combination with each latent failure condition not shown to be extremely remote, and from all combinations of failures not shown to be extremely improbable. The effects of manufacturing variab ility, aging, wear, corrosion, and likely damage must be considered.

The Extent of Relief Sought and Reason(s):

Regulation Compliance requires: Relief is Necessary because:
14 CFR 25.901(c)

Amendment 25-126 no single failure or malfunction or probable

combination of failures will jeopardize safe operation Direct compliance would require excessive design changes for production

and retrofit of in-ser vice airplanes using the redesigned FQPU for replacement or repair. Changes include the following:Enclosure to RA-12-04444

Petition for Exemption from 14 CFR 25.981(a )(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126, Code of Federal Regulations

2 Redesign of the Airp lane Wiring System to ensure FQIS wire separation for numerous airplane configurations.

Make new tank penetrations and procure new in-tank wiring harnesses.

Modify the Fuel Quantity Processor Unit (FQPU) and associated connectors. The solution would require a FQIS architecture change to relocate the FQPU

and consider Remote Data Connectors (RDCs).

In-tank component changes (new brackets, potential need for shorter probes,

revised in-tank wire harness and retention means).

Software changes related to Fuel Tank Gauging Function (to account for capacitance changes if shorter in-tank probes are required). 14 CFR 25.981(a)(3)

Amendment 25-125 An ignition source could not result from each single failure, from each single failure in

combination with each latent

failure condition not shown to be extremely remote, and from

all combinations of failures not shown to be extremely improbable. The effects of manufacturing variability, aging, wear, corrosion, and likely damage must be

considered. Same as above

Description of Issue:

The 767 Fuel Quantity Processer Unit (FQPU) us es digital ARINC 429 busse s to receive/transmit data to the flight deck, EICAS and refueling panels through two redundant Input/Output ChannelEnclosure to RA-12-04444

Petition for Exemption from 14 CFR 25.981(a )(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126, Code of Federal Regulations

3 (IOC) circuit cards. The current pr oduction IOC card utilizes many in tegrated electronic microchips

to transmit and receive the ARINC 429 data. One of the microchips, a programmable logic device (PLD), which is involved with comm unication to the flight deck and re fueling panel, has been out of production for several years, and th e supply is now becoming exhausted

.

In February 2012 the FQPU supplier informed Boei ng that the supply of this particular ARINC 429 chip used on the two IOC cards and also on the BI TE card will run out in late 2012 and that it is not possible to find alternate sources for procurement of the current chip. The supplier initiated a contract with another chip manufacturer to develop a replacement chip to the unchanged requirements of the original chip as defined by the supplier’s Specification Control Document. The new chip, by requirement, is an identical form -fit-function replacement to the current production chip. In August, Boeing and the supplier reviewed the existing stores of parts and were able to extend the supply through Ja nuary 2013 with a possible extension into March 2013.

There is concern on the part of The Boeing Company that replacing this obsolescent chip with an identical form-fit-function chip could result in a requirement to show full compliance to 25.901(c) Amendment Level 126 and 25.981(a)(3) Amendment Level 125 for the FQIS at the system level. If this were indeed the case, this would require a significant number of cha nges associated with the FQIS intrinsically safe side wiring.

The reasons for this exemption petition is that full compliance to these rules for the 767 would require extensive system design changes which are not in the public’s intere st, do not substantially improve the safety of the current airplane design, and cannot be accomplished in the very short time prior to exhaustion of the parts necessary to deliv er airplanes.

The system has been shown compliant to §25.1309; however, presently both §25.901(c) and §25.981(a)(3) have additional failure combination re quirements. For systems that may cause a catastrophic hazard, §25.1309 requires no single failure and no combination of failures greater than extremely improbable; §25.901(c) requi res no single failure or probable combination of failures; and §25.981(a)(3) requires no single failure, no single plus latent (greater than ex tremely remote), and no multiple combination greater than extremely improbable.

This exemption is being sought for the no single plus latent (greater than extremely remote) as is stated in §25.981(a)(3) a nd interpreted by the FAA for §25.901(c) . And exemption is also being sought for the non-environmental aspects of §25.901(c) provided by FAA interpretation, and the explicit §25.981(a)(3) re quirements of manufacturing variabili ty, aging, wear, corrosion, and likely damage, as these considerations are already cove red by factory manufacturing processes, and airline maintenance of the type design of airplane.

Statement of Public Interest:Enclosure to RA-12-04444

Petition for Exemption from 14 CFR 25.981(a )(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126, Code of Federal Regulations

4 Without exemption relief the following airplane ch anges would be required for production and fleet retrofit so that the changed FQPU could be used for production airplanes a nd repair or replacement in the existing fleet.

 New system architecture and extensive airpla ne wiring changes to en sure adequate wire separation throughout the fuel quantity indication system.

 In-tank component changes (new brackets, potential need for s horter probes, revised in-tank wire harness and retention means).

 Software changes related to Fuel Tank Gaugi ng Function and Safety function if shorter probes are required.

The time needed to successfully design and implement the system changes to comply would seriously impact the continued pr oduction of the 767 and could result in cancellation of significant customer airplane orders. To release new Boei ng design architecture requirements and to have a supplier develop and qualify new software and hard ware to these new requirements would take years, and no 767 airplane deliveries could be comple ted during that time. Also, if these changes are required to airplanes that are in the delivered flee t, operators would need to remove the airplanes from service for lengthy and expensive modifica tions whenever existing FQPUs needed to be replaced. These new design changes would not pr ovide any economic benefit to the operators or public and do not provide any significant benefit or increased level of safety over new production airplanes or in-service airplane s which have the Nitrogen Genera tion System (NGS) installed. The current FQIS system has been thoroughly evaluate d for safety aspects as was required per SFAR88 for the Fuel Quantity Indicating System, and no significant safety issues were identified.

The granting of this exemption is in th e public interest for the following reasons:

1. Denial of this petition for exemption will result in an estimated 3-year delay in the delivery of 767 airplanes due to the redesign of the FQIS system to be fully compliant to §25.981(a)(3). This would result in subsequent impact to airline operations, as the 767 would no longer be available. Further, there will be no significant change to the safety of production airplanes which are equipped with NGS.

2. Denial of this petition for exemption woul d result in the airlines having to perform extraordinary work which would result in disr uption of operations and would pose significant burden on the airlines to make the airplane changes outlined for installation of a §25.901(c) and §25.981(a)(3) compliant FQIS whenever an in -service FQPU fails w ithin their fleet.

Statement of No Adverse Effect on Safety:

The replacement of the existing ARINC 429 chip with the new replacement chip does not adversely affect the safety of the current sy stem. There is no threat to fuel tank ignition from the IOC or the BITE card within the FQPU because there is no electrical conducto r connection between the boardsEnclosure to RA-12-04444

Petition for Exemption from 14 CFR 25.981(a )(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126, Code of Federal Regulations

5 with the obsolete chip and the fuel tank. Hence, the change has no relation to fuel tank ignition prevention, does not impact line replaceable unit (LRU ) or system level failure modes, effects, or probabilities relative to fuel ta nk ignition and therefor e has no impact to airplane safety.

The 767 FQIS was found to be compliant to §25.901(c) during airplane type certification and since then Boeing has done the SFAR88 safety assessment and has increased the airplane fuel system safety with installation of a hot short protector for the densitometer and with installation of a NGS for the center fuel tanks. The proposed change has no impact on any of the SFAR88 related

assessments

Even prior to the implementation of NGS which fu rther reduces any risk, the Boeing assessment was that the risks for the 767 FQIS installation were ex tremely improbable, which is the typical industry and CFR §25.1309 standard for an ac ceptable systems installation.

Request to Waive Publication and Comment:

Given the time-sensitive nature of this request fo r exemption, Boeing respectfully requests that the FAA waive the “publication and co mment” step in the process for making a final decision on this exemption. In addition to the timeliness concern, it is the Boeing position th at the safety-associated aspects related to this system ha ve been fully vetted in the pub lic forum as part of the SFAR88 project. Expedited treatment is necessary to prevent interruption to 767 production deliveries.

Privileges of the Exemption Outside the United States:

Per 14 CFR 11.81(h), Boeing requests that the privile ges of this exemption be extended outside the United States. This extension of pr ivileges is necessary for operati ons based within foreign countries having bilateral agreements with the United States accepting FAA 14 CFR part 25 as their

airworthiness standards for tr ansport category aircraft.

Conclusion:

Boeing is petitioning for an exemption from th e provisions of 14 CFR 25.901(c)[25-126] and 14 CFR 25.981(a)(3)[25-125] at the syst em level as they apply to the FQIS installed on the 767-200, 767-300, 767-300F, 767-400ER airplanes for the FQPU part s obsolescence change described above.

Replacement of the ARINC 429 chip within the IOC cards and the BITE card of the current FQPU is necessary due to obsolescence of the current chip. The re-designed chip will not impact the FQIS safety. Incorporation of the NGS for all 767 prod uction airplanes and retr ofit of passenger models has further improved fuel tank safety and reduced fleet safety risks.

Granting this exemption will allow use of this replacement chip within the IOC card and BITE card of the current production FQPU fo r repairs without extensive rewo rk to in-service aircraft.Enclosure to RA-12-04444

Petition for Exemption from 14 CFR 25.981(a )(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126, Code of Federal Regulations

6 Summary to be published in the Federal Register :

PETITIONER : Boeing Commercial Airplanes

SECTION OF 14 CFR AFFECTED : 14 CFR 25.981(a)(3) Amendment 25-125 and 14 CFR 25.901(c) Amendment 25-126

DESCRIPTION OF RELIEF SOUGHT :

The Boeing Company is petitioning for an exemption from the provisions of 14 CFR 25.901(c)[25-126] and 14 CFR 25.981(a )(3)[25-125] at the system le vel as they apply to the FQIS installed on the 767-200, 767-300, 767-300F, 767-400ER airplanes for an FQPU parts

obsolescence modification.