Airworthiness Directives; Nordskog Water Heaters and Coffee Makers as Installed in Various Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 94-NM-01-AD; Amendment 39-8955; AD 94-14-03]

Airworthiness Directives; Nordskog Water Heaters and Coffee

Makers as Installed in Various Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD),

applicable to certain Nordskog water heaters and coffee makers. This

amendment requires an inspection to determine whether certain

discrepant pressure relief valves have been installed in certain galley

water heaters and coffee makers; and either replacement of the

discrepant valves, or discontinued use of the water heaters or coffee

makers and installation of placards indicating that these units are not

to be used. This amendment is prompted by reports of injuries to cabin

crew members that resulted from explosions of galley water heaters. The

actions specified by this AD are intended to prevent explosions of

galley water heaters and coffee makers, and subsequent injuries to

passengers or cabin crew members.

DATES: Effective August 1, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of August 1, 1994.

ADDRESSES: The service information referenced in this AD may be

obtained from Aircraft Products Company, 12807 Lake Drive, P.O. Box

130, Delray Beach, Florida 33447-0130. This information may be examined

at the Federal Aviation Administration (FAA), Transport Airplane

Directorate, Rules Docket, 1601 Lind Avenue, SW., Renton, Washington;

or at the FAA, Los Angeles Aircraft Certification Office (ACO), 3229

East Spring Street, Long Beach, California; or at the Office of the

Federal Register, 800 North Capitol Street, NW., suite 700, Washington,

DC.

FOR FURTHER INFORMATION CONTACT: Walter Eierman, Systems and Equipment

Branch, ANM-131L, FAA, Transport Airplane Directorate, Los Angeles ACO,

3229 East Spring Street, Long Beach, California 90806-2425; telephone

(310) 988-5336; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal

Aviation Regulations (14 CFR part 39) to include an airworthiness

directive (AD) that is applicable to certain Nordskog water heaters and

coffee makers was published in the Federal Register on March 16, 1994

(59 FR 12203). That action proposed to require an inspection to

determine whether certain discrepant pressure relief valves have been

installed in certain galley water heaters and coffee makers; and either

replacement of the discrepant valves, or discontinued use of the water

heaters or coffee makers and installation of placards indicating that

these units are not to be used.

Interested persons have been afforded an opportunity to participate

in the making of this amendment. Due consideration has been given to

the comments received.

Several commenters support the proposal.

Another commenter supports the proposed AD action, but requests

that it be issued as an immediately adopted rule, in light of the

potential for serious injury to passengers and cabin crew members that

is associated with exploding water heaters and coffee makers. This

commenter points out that AD 93-23-01, amendment 39-8735 (58 FR 61618,

November 22, 1993), addressed this same problem in other water heaters

and coffee makers using the same pressure relief valves, and it was

made effective immediately, without prior opportunity for notice and

public comment. This commenter questions whether the unsafe condition

is any ``less'' for the units addressed by the proposal than for those

addressed by AD 93-23-01. The FAA responds by noting that the incident

reports that prompted the issuance of AD 93-23-01 involved units

equipped with an integral check valve; AD 93-23-01 applies only to

units with the integral check valve installation. At the time that AD

93-23-01 was issued, the FAA was in the process of evaluating the need

for additional AD action to address other installations that

incorporate the same pressure relief valve design. The FAA found that

Nordskog water heaters and coffee makers without the integral check

valve could use the same pressure relief valve in other applications

and, therefore, could also be subject to the same unsafe condition.

However, because there had been no service history of incidents

involving units without the integral check valve, the FAA could not

demonstrate that the safety concern was so critical that it should

preclude the opportunity for prior notice and public comment on this

rule.

Two commenters do not consider that AD action is appropriate to

address a ``non-critical'' application of the subject valve. These

commenters point out that AD 93-23-01 implemented the recommendations

of Nordskog Service Bulletin 93-34, which targeted the ``critical''

valve installations. However, the proposed AD would implement the

recommendations of Nordskog Service Bulletin 93-35, which addresses

``non-critical'' installations of the valve. In light of this, the

commenters contend that the AD is unnecessary. The FAA does not concur.

The FAA acknowledges that AD 93-23-01 addresses units that incorporate

the subject valve as an integral check valve, which may be viewed as a

``critical'' application of the valve; it was a unit equipped with this

integral check valve that exploded during the incident that prompted

issuance of that AD. However, as discussed in the previous comment, the

FAA has determined that water heaters and coffee makers that are not

equipped with the integral check valve but use the same pressure relief

valve addressed by AD 93-23-01, may also be subject to the same unsafe

condition addressed by that AD. Although the commenters may view the

component design of the units addressed by this AD action as ``less

critical'' than those addressed by AD 93-23-01, the FAA has received no

data to demonstrate that the subject relief valve is not necessary to

assure system safety. Therefore, the FAA considers this AD action to be

both appropriate and warranted.

One commenter requests that the proposed rule be revised the permit

the installation of the discrepant NUPRO pressure relief valve after

the effective date of the AD and until the compliance time for

inspection. This commenter points out that proposed paragraph (b) would

require that, as of the effective date of the rule, no operator would

be allowed to install a discrepant valve on any airplane; however,

operators would have up to 12 months to remove any discrepant valve

that is currently installed on the airplane. The FAA does not concur in

this case. Removing an unsafe condition that already exists on an

airplane necessarily involves performing maintenance on the airplane,

and the FAA always provides some kind of ``grace period'' in order to

minimize disruption of operations. On the other hand, prohibiting

installation of spares that have been determined to create an unsafe

condition does not require any additional maintenance activity; it

simply requires use of one part rather than another. In general, once

an unsafe condition has been determined to exist, it is the FAA's

normal policy not to allow that condition to be introduced into the

fleet. In developing the technical information on which every AD is

based, one of the important considerations is the availability of parts

that the AD will require to be installed. When it is determined that

those (safe) parts are immediately available to operators, it is the

FAA's policy to prohibit installation of the unsafe parts after the

effective date of the AD.

Further, the FAA considers that the period of time between

publication of the final rule AD in the Federal Register and the

effective date of the final rule (usually 30 days) is sufficient to

provide operators with an opportunity to determine their immediate need

for modified spares and to obtain them. Of course, in individual cases

where this is not possible, every AD contains a provision that allows

an operator to obtain an extension of compliance time based upon a

specific showing of need. The FAA considers that this policy does

increase safety and does not impose undue burdens on operators.

One commenter is concerned about the thermostat installed on the

water heaters and coffee makers equipped with the subject NUPRO

pressure relief valves, and its involvement in the incident of

explosion of the water heater. This commenter assumes that the incident

was the result of one of two possible failure paths: Either the

thermostat failed closed and the pressure relief valve failed closed;

or the power relay failed closed and the pressure relief valve failed

closed. This commenter indicates that the proposed rule does not

address these possible failure paths or the fact that failures of the

thermostat or relay are non-indicating by themselves. The FAA

acknowledges that this commenter's assumptions about the failure paths

is reasonable. Although a failure other than that of the relief valve

could not be identified, some failure apparently occurred in the

temperature control system to cause the pressure to build up beyond its

normal level. Generally, it is expected that the temperature control

system will fail sometime during its service life; the relief valve is

in the system to address that failure. Although increased redundancy

and failure monitoring in the temperature control system would be two

ways of improving system safety, those methods are not considered

necessary in this case. Replacement of the discrepant valve with the

improved valve will address the failure scenario that actually

occurred.

This commenter also is concerned about part identification of

inserts in the affected water heaters and coffee makers, and the need

for a possible design change of NUPRO relief valves that have a common

design type. Since these issues do not directly concern this rulemaking

action, the FAA has passed the commenter's suggestions on to the

appropriate manufacturer. -

After careful review of the available data, including the comments

noted above, the FAA has determined that air safety and the public

interest require the adoption of the rule as proposed.

The FAA is aware that the subject water heaters and coffee makers

are installed in various airplanes. There are approximately 300 of

these airplanes in the worldwide fleet, the FAA estimates that 200

airplanes are of U.S. registry. It will take approximately 2 work hours

per airplane to accomplish the proposed actions, and the average labor

rate is $55 per work hour. (There are approximately 4 water heaters

and/or coffee makers installed on each airplane.) The cost of required

parts is expected to be negligible. Based on these figures, the total

cost impact of this AD on U.S. operators is estimated to be $22,000, or

$110 per airplane.

The total cost impact figure discussed above is based on

assumptions that no operator has yet accomplished any of the

requirements of this AD action, and that no operator would accomplish

those actions in the future if this AD were not adopted.

The regulations adopted herein will not have substantial direct

effects on the States, on the relationship between the national

government and the States, or on the distribution of power and

responsibilities among the various levels of government. Therefore, in

accordance with Executive Order 12612, it is determined that this final

rule does not have sufficient federalism implications to warrant the

preparation of a Federalism Assessment.

For the reasons discussed above, I certify that this action: (1) Is

not a ``significant regulatory action'' under Executive Order 12866;

(2) is not a ``significant rule'' under DOT Regulatory Policies and

Procedures (44 FR 11034, February 26, 1979); and (3) will not have a

significant economic impact, positive or negative, on a substantial

number of small entities under the criteria of the Regulatory

Flexibility Act. A final evaluation has been prepared for this action

and it is contained in the Rules Docket. A copy of it may be obtained

from the Rules Docket at the location provided under the caption

ADDRESSES.

List of Subjects in 14 CFR Part 39

Air transportation, Aircraft, Aviation safety, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends part 39 of

the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

1. The authority citation for part 39 continues to read as follows:

Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C.

106(g); and 14 CFR 11.89.

39.13 [Amended]

2. Section 39.13 is amended by adding the following new

airworthiness directive:

94-14-03 Nordskog Industries, Inc.: Amendment 39-8955. Docket 94-

NM-01-AD.

Applicability: Nordskog water heaters and coffee makers, as

listed in Nordskog Industries, Inc., Service Bulletin SB-93-35,

dated October 21, 1993; as installed in, but not limited to, Boeing

Model 727, 737, 747, 757, and 767 series airplanes; McDonnell

Douglas Model DC-9, DC-9-80, and DC-10 series airplanes, and MD-11

airplanes; Lockheed Model L-1011 series airplanes; Airbus Industrie

Model A300, A310, and A320 series airplanes; Gulfstream Model G-1159

series airplanes and Model G-IV airplanes; de Havilland, Inc., Model

DHC-8 series airplanes; Dassault-Aviation Model Mystere-Falcon 50,

200, and 900 series airplanes; Canadair Model CL-600-1A11 (CL-600),

CL-600-2A12 (CL-601), and CL-600-2B16 (CL-601-3A and -3R) and CL-

600-2B19 series airplanes; and Fokker Model F27 and F28 series

airplanes; certificated in any category.

To prevent explosions of galley water heaters and coffee makers,

and subsequent injuries to passengers or cabin crew members,

accomplish the following:

(a) Within 12 months after the effective date of this AD,

perform a one-time inspection to determine whether a NUPRO pressure

relief valve having part number (P/N) SS-2C4-65 has been installed,

in accordance with Nordskog Industries, Inc., Service Bulletin SB-

93-35, dated October 21, 1993. If any NUPRO pressure relief valve

having P/N SS-2C4-65 has been installed, prior to further flight,

accomplish either paragraph (a)(1) or (a)(2) of this AD.

(1) Remove the NUPRO pressure relief valve having P/N SS-2C4-65

and install a new, improved NUPRO pressure relief valve having P/N

SS-CHF2-65, in accordance with the service bulletin. Or

(2) Deactivate any Nordskog water heater or coffee maker listed

in the service bulletin on which a NUPRO pressure relief valve

having P/N SS-2C4-65 has been installed, and install a placard

stating, ``Not to be used.''

(b) As of the effective date of this AD, no person shall install

a NUPRO pressure relief valve having P/N SS-2C4-65 on any airplane.

(c) An alternative method of compliance or adjustment of the

compliance time that provides an acceptable level of safety may be

used if approved by the Manager, Los Angeles Aircraft Certification

Office (ACO), FAA, Transport Airplane Directorate. Operators shall

submit their requests through an appropriate FAA Principal

Maintenance Inspector, who may add comments and then send it to the

Manager, Los Angeles ACO.

Note: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Los Angeles ACO.

(d) Special flight permits may be issued in accordance with

sections 21.197 and 21.199 of the Federal Aviation Regulations (14

CFR 21.197 and 21.199) to operate the airplane to a location where

the requirements of this AD can be accomplished.

(e) The inspection and installation shall be done in accordance

with Nordskog Industries, Inc., Service Bulletin SB-93-35, dated

October 21, 1993. This incorporation by reference was approved by

the Director of the Federal Register in accordance with 5 U.S.C.

552(a) and 1 CFR part 51. Copies may be obtained from Aircraft

Products Company, 12807 Lake Drive, P.O. Box 130, Delray Beach,

Florida 33447-0130. Copies may be inspected at the FAA, Transport

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or

at the FAA, Los Angeles Aircraft Certification Office (ACO), 3229

East Spring Street, Long Beach, California; or at the Office of the

Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(f) This amendment becomes effective on August 1, 1994.

Issued in Renton, Washington, on June 22, 1994.

S.R. Miller,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-15597 Filed 6-29 -94; 8:45 am]

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