[Federal Register Volume 64, Number 128 (Tuesday, July 6, 1999)]
[Proposed Rules]
[Pages 36307-36318]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-16752]


=======================================================================
-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-CE-67-AD]
RIN 2120-AA64


Airworthiness Directives; Cessna Aircraft Company 300 and 400 
Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

-----------------------------------------------------------------------

SUMMARY: This document proposes to supersede Airworthiness Directive 
(AD) 75-23-08 R5, which currently requires repetitively inspecting and 
replacing or repairing the exhaust system on certain Cessna Aircraft 
Company (Cessna) 300 and 400 series airplanes. The proposed AD would 
replace the inspections and replacements that are required by AD 75-23-
08 R5 with inspections and replacements containing new simplified 
procedures for all 300 and 400 series airplanes (models affected by the 
current AD plus additional models). The proposed AD would also revise 
the inspection intervals and would require replacing certain 
unserviceable parts and removing the exhaust system for detailed 
inspections at regular intervals. The proposed AD is the result of 
numerous incidents and accidents relating to the exhaust systems on 
Cessna 300 and 400 series airplanes dating from the middle 1970's to 
the present, including six incidents since issuance of AD 75-23-08 R5 
where exhaust problems were cited. The actions specified by the 
proposed AD are intended to detect and correct cracks and corrosion in 
the exhaust system, which could result in exhaust system failure and a 
possible uncontrollable in-flight fire with pilot and/or passenger 
injury.

DATES: Comments must be received on or before August 9, 1999.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Central Region, Office of the Regional Counsel, 
Attention: Rules Docket No. 97-CE-67-AD, Room 1558, 601 E. 12th Street, 
Kansas City, Missouri 64106. Comments may be inspected at this location 
between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted.

FOR FURTHER INFORMATION CONTACT: Paul O. Pendleton, Aerospace Engineer, 
FAA, Wichita Aircraft Certification Office, 1801 Airport Road, Room 
100, Wichita, Kansas 67209; telephone: (316) 946-4143; facsimile: (316) 
946-4407.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications should identify the Rules Docket number 
and be submitted in triplicate to the address specified above. The FAA 
believes that the proposed regulation may have a significant economic 
impact on a substantial number of small businesses. Due to the urgent 
nature of the safety issues addressed, the FAA has been unable to 
complete a preliminary regulatory flexibility analysis prior to 
issuance of the NPRM. A final regulatory flexibility analysis will be 
completed before, or within 180 days of issuance of, the final rule. To 
assist in this analysis, the FAA is particularly interested in 
receiving information on the impact of the proposed rule on small 
businesses and suggested alternative methods of compliance that reduce 
or eliminate such impacts. All communications received on or before the 
closing date for comments, specified above, will be considered before 
taking action on the proposed rule. The proposals contained in this 
notice may be changed in light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report that summarizes each FAA-public contact concerned 
with the substance of this proposal will be filed in the Rules Docket.

[[Page 36308]]

    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 97-CE-67-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Central Region, Office of the Regional Counsel, Attention: 
Rules Docket No. 97-CE-67-AD, Room 1558, 601 E. 12th Street, Kansas 
City, Missouri 64106.

Discussion

    AD 75-23-08 R5, Amendment 39-5451, currently requires repetitively 
inspecting, using visual methods, the exhaust system on certain Cessna 
300 and 400 series airplanes; and repairing or replacing any 
unserviceable parts.
    Cessna and the FAA performed extensive investigation and found the 
following possible causes and effects of these exhaust problems:

--Significant vibration between the beam-mounted engine and the 
firewall-mounted turbocharger;
--Leaking exhaust gases, which can cause fuel line failure because the 
fuel lines behind the firewall overheat and rupture. (Most of these 
fuel lines cannot be isolated or shut-off);
--Reduced structural strength of the engine mount beams and canted 
bulkheads as a result of exposure to high heat, which could compromise 
the engine installation; and
--Structural failure of the wing or loss of flight control that results 
from an in-flight fire.

    The FAA issued AD 75-23-08 and five subsequent revisions to this 
AD, including the current one referenced above, as an attempt to manage 
these problems through repetitive visual inspections.

Actions Since Issuance of Previous Rule

    In the 20 plus years since the issuance of AD 75-23-08, failures of 
exhaust systems on Cessna 300 and 400 series airplanes have continued 
to occur and have contributed to fatalities. The FAA, the National 
Transportation Safety Board (NTSB), and Cessna have conducted numerous 
tests and analysis on the exhaust system configurations in an attempt 
to resolve the repeated problems and to alleviate these failures.
    The FAA and the NTSB have issued several safety recommendations to 
provide guidance on how to alleviate problems with the exhaust systems 
on Cessna 300 and 400 series airplanes. From these recommendations, the 
FAA has developed new service information (included as an Appendix to 
this AD) and Cessna has revised the maintenance and service manuals. 
The FAA believes that this new information should help to reduce the 
confusion of the requirements in the current action and simplify the 
procedures.
    A recent fatal accident has occurred involving a Cessna Model 421B 
airplane. While not implicated in the cause of the accident, the FAA 
and the NTSB have determined that the exhaust system on the accident 
airplane was in a condition of imminent catastrophic failure. The 
airplane records indicate that the exhaust system inspection and 
replacement requirements of AD 75-23-08 R5 had been accomplished.

The FAA's Determination

    After examining the circumstances and reviewing all available 
information related to the incidents described above, including the 
referenced service information, the FAA has determined that AD action 
should be taken to detect and correct cracks and corrosion in the 
exhaust system, which could result in exhaust system failure and a 
possible uncontrollable in-flight fire. Exposure to these conditions 
could cause injury to the pilot and passengers during flight.

Explanation of the Provisions of the Proposed AD

    Since an unsafe condition has been identified that is likely to 
exist or develop in other Cessna 300 and 400 series airplanes of the 
same type design, the FAA is proposing an AD to supersede AD 75-23-08 
R5. The proposed AD would replace the inspections and replacements that 
are required by AD 75-23-08 R5 with inspections and replacements 
containing new simplified procedures for all 300 and 400 series 
airplanes (models affected by the current AD plus additional models). 
The proposed AD would also revise the inspection intervals and would 
require replacing certain unserviceable parts and removing the exhaust 
system for detailed inspections at regular intervals. Provisions of the 
proposed AD include:

--Prohibiting patch-type repairs; and
--Removing the exhaust system and sending it to a designated facility 
for metallic identification, airworthiness determinations, and repair 
or replacement of any unserviceable parts.

Service Information

    In the future, Cessna may develop service information or additional 
maintenance and/or service manual revisions to address this issue. The 
FAA will issue alternative methods of compliance to this AD if the 
procedures are deemed acceptable to address the unsafe condition 
specified in the proposed AD.

Cost Impact

    The FAA estimates that 6,500 airplanes in the U.S. registry would 
be affected by the proposed AD. The cost of the proposed inspections 
would be as follows at an average labor rate of approximately $60 per 
hour. The cost of any necessary repair depends on the extent of the 
rework and replacement needed based on the results of the proposed 
inspections.

--The proposed repetitive 50-hour time-in-service (TIS) visual 
inspections of the exhaust system would take approximately 3 workhours 
to accomplish, with a labor cost of $180 per airplane for each 
inspection;
--The proposed repetitive 100-hour TIS visual inspections of the 
removed tailpipes would take approximately 1 workhour per tailpipe to 
accomplish, with a labor cost of $120 per airplane for each proposed 
inspection;
--The proposed inspection of the engine beams and canted bulkheads, as 
a result of damage to the tailpipes, would take approximately 3 
workhours to accomplish, with a labor cost of $180 per airplane;
--The proposed inspection of the fuel tubing behind the firewall, as a 
result of damage to the tailpipes, engine beams, and canted bulkheads, 
would take approximately 16 workhours to accomplish, with a labor cost 
of $960 per airplane;
--The proposed replacement of the fuel tubing, if necessary, would take 
approximately 30 workhours to accomplish, with a labor cost of $1,800 
per airplane;
--The proposed 500-hour TIS proposed requirement of removing and 
shipping the exhaust system to an approved facility would take 
approximately 8 workhours, with a labor cost of $480. The cost of 
shipping the exhaust system to the facility and the inspections by the 
facility is estimated at $500;
--The proposed repetitive pressure test is estimated to take 1 
workhour, with a labor cost of $60 per airplane; and
--The proposed V-band clamp replacement is estimated to take 1 
workhour, with a labor cost of $60 per airplane.

    The total cost impact on the U.S. operators for the proposed 
initial inspections is estimated to be

[[Page 36309]]

$28,210,000, or $4,340 per airplane. The maximum expense for full 
exhaust parts replacement is estimated to be approximately $60,000 per 
airplane. These figures do not take into the account the costs of any 
repetitive inspections or repairs or replacements that would be 
necessary if the FAA adopted the proposed rule. The FAA has no way of 
determining the number of repetitive inspections an owner/operator will 
incur over the life of the airplane, or the extent of the repairs and 
replacements that may be necessary for any affected airplane.

Compliance Time of This AD

    Certain repetitive inspections of the proposed AD are presented in 
both calendar time and hours time-in-service (TIS). The unsafe 
condition specified in the proposed AD is a result of the stress 
cracking and/or corrosion that results over time. Stress corrosion 
starts as a result of high local stress incurred through operation of 
the affected part (the exhaust systems). Corrosion can then develop 
regardless of whether the airplane is in operation. The cracks may not 
be noticed initially as a result of the stress loads, but could then 
progress as a result of corrosion. The stress incurred during flight 
operations (while in-flight) or temperature changes (either while in-
flight or on the ground) could then cause rapid crack growth. In order 
to assure that these stress corrosion cracks do not go undetected, a 
compliance time of specific hours TIS and calendar time (whichever 
occurs first) is proposed.

Regulatory Impact

    The regulations proposed herein would 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 
proposal would 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) if promulgated, 
may have a significant economic impact on a substantial number of small 
entities under the criteria of the Regulatory Flexibility Act. The FAA 
is currently conducting a Regulatory Flexibility Determination and 
Analysis and has considered alternatives to the proposed AD that could 
minimize the impact on small entities.
    After careful consideration, the FAA determined that AD action is 
the best course of action to address the unsafe condition specified in 
this document; and (2) the situation does not warrant waiting for the 
completion of the Regulatory Flexibility Determination and Analysis 
before issuing the NPRM. When completed, a copy of the Regulatory 
Flexibility Determination and Analysis will be placed in the Docket 
file and can be obtained at the address specified in the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 14 
CFR part 39 of the Federal Aviation Regulations as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing Airworthiness Directive 
(AD) 75-23-08 R5, Amendment 39-5451, and by adding a new AD to read as 
follows:

Cessna Aircraft Company: Docket No. 97-CE-67-AD; Supersedes AD 75-
23-08 R5, Amendment 39-5451.

    Applicability: Models T310P, T310Q, T310R, 320, 320A, 320B, 
320C, 320D, 320E, 320F, 320-1, 335, 340, 340A, 321 (Navy OE-2), 401, 
401A, 401B, 402, 402A, 402B, 402C, 404, 411, 411A, 414, 414A, 421, 
421A, 421B, and 421C airplanes, all serial numbers, certificated in 
any category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (k) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated in the compliance table in 
Figure 1 of this AD, unless already accomplished.
    To detect and correct cracks and corrosion in the exhaust 
system, which could result in exhaust system failure and a possible 
uncontrollable in-flight fire with pilot and/or passenger injury, 
accomplish the following:
    (a) The following paragraphs present the type of individuals who 
have the authority to accomplish the actions of this AD:
    (1) Repairs: Required to be accomplished at an FAA-approved 
repair facility.
    (2) Replacements: Required to be accomplished in accordance with 
the appropriate Cessna Service Manual and must be accomplished by a 
person holding a currently effective mechanic certificate with both 
an airframe and powerplant (A&P) rating or by an individual 
authorized to represent an FAA-approved repair station.
    (3) Visual inspections except for paragraphs (f) and (i) of this 
AD: Required to be accomplished by a person holding a currently 
effective mechanic certificate with both an airframe and powerplant 
(A&P) rating.

BILLING CODE 4910-13-U

[[Page 36310]]

[GRAPHIC] [TIFF OMITTED] TP06JY99.005



BILLING CODE 4910-13-C

[[Page 36311]]

    (b) At the compliance time specified in Figure 1 of this AD, 
visually inspect the exhaust system for burned areas, cracks, or 
looseness. If any area of the exhaust system shows damage as defined 
in the Appendix of this AD, prior to further flight, repair or 
replace the damaged part.
    (c) At the compliance time specified in Figure 1 of this AD, 
remove the tailpipes and visually inspect for cracks, corrosion, 
holes, or distortion.
    (1) If no crack, corrosion, hole, or distortion is found, 
continue to visually inspect at intervals indicated in Figure 1 of 
this AD.
    (2) If a crack, corrosion, hole, or distortion is found during 
any inspection, prior to further flight, repair or replace the 
tailpipe.
    (3) When a new tailpipe is installed after the effective date of 
this AD, terminate the 100-hour time-in-service (TIS) repetitive 
inspections required as specified in Figure 1 of this AD until the 
accumulation of 500 hours TIS or 5 years from the installation date, 
whichever occurs first, at which time continue the 100-hour TIS 
inspection intervals.
    (d) At the compliance time specified in Figure 1 of this AD, 
visually inspect the outboard engine beam (adjacent to the tailpipe) 
and the canted bulkheads for signs of distress, chafing, corrosion, 
or cracking. Even though some airplanes may have stainless steel 
engine beams, carefully inspect the areas of contact between the 
engine beam and canted bulkhead for corrosion.
    (1) If damage to the engine beams is found or there is evidence 
of overheating on the firewall, prior to further flight, replace the 
firewall and the aluminum fuel lines behind the firewall. Stainless 
steel fuel lines are available from the Cessna Aircraft Company. 
Replacement of the fuel lines behind the firewall may require 
removing and replacing the firewall or accomplishing major repair of 
the firewall.
    (2) Prior to further flight, repair any distress, chafing, 
corrosion, or cracking on the engine beams or canted bulkheads in 
accordance with data provided by any individual or facility that is 
authorized by the FAA to perform the necessary repairs or provide 
the FAA-approved data to authorized personnel for repair of these 
items.
    (e) At the compliance time specified in Figure 1 of this AD, 
inspect the exhaust system and perform a pressure test in accordance 
with the Appendix of this AD. If any condition as specified in the 
Appendix of this AD is found, prior to further flight, repair or 
replace the affected parts.
    (f) At the compliance time specified in Figure 1 of this AD, 
remove the exhaust system from the slip joints and aft to all 
turbocharger-attached components and send to an FAA-approved 
manufacturing and repair facility that is authorized by the FAA to 
perform material and condition determinations, and prior to further 
flight, accomplish any necessary repairs on these items.

    Note 2: The following repair facilities have been approved as of 
the effective date of this AD. A current list of FAA-approved 
facilities can be obtained from the FAA, Wichita Aircraft 
Certification Office, 1801 Airport Road, Room 100, Wichita, Kansas 
67209; Attention: Paul O. Pendleton, Aerospace Engineer; telephone: 
(316) 946-4143; facsimile: (316) 946-4407:

Wall Colmony Corp., 4700 S.E. 59th St., Oklahoma City, OK 73135, 
(405) 672-1361
Knisley Welding Inc., 3450 Swetzer Road, Loomis, CA 95650, (916) 
652-5891
Heliarc Welding Service, 3965 Newport St., 73135 Denver, CO 80207-
73135, (303) 672-1361

    Note 3: The FAA-approved manufacturing and repair facilities 
will perform the following and provide information to be utilized 
for future actions required by this AD:
     Determine the airworthiness of the exhaust system 
parts;
     Measure for the minimum acceptable material thickness 
of .025 inch;
     Determine the airworthiness of previous repairs (multi-
seam welds and patch-type welds are not considered airworthy);
     Repair or replace all unserviceable parts (no multi-
seam or patch-type weld repairs are permitted);
     Determine the material type of the exhaust system 
(i.e., Inconel or stainless steel); and
     Stamp the material type with an ``I'' for Inconel or 
``SS'' for stainless steel, the name of the facility making the 
determination, and the date on the exhaust system.

    (g) At the compliance time specified in Figure 1 of this AD, 
replace all V-band clamps per the appropriate Cessna Service Manual.
    (h) At the compliance time specified in Figure 1 of this AD, 
disassemble and visually inspect the slip joint for freedom of 
motion. If the slip joint is seized or frozen, prior to further 
flight, replace the slip joint.
    (i) At the compliance time specified in Figure 1 of this AD, 
remove the exhaust system from the slip joints and aft to all turbo-
charger attached components, and send to any FAA-approved exhaust 
repair facility. The FAA-approved exhaust repair facility will 
inspect this portion of the exhaust system for serviceable condition 
and make any necessary repairs to these items. No patch-type or 
multi-seam weld repairs are permitted.
    (j) 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. Isolation of the 
fuel cross feed lines behind the firewall may be required.
    (k) An alternative method of compliance or adjustment of the 
initial or repetitive compliance times that provides an equivalent 
level of safety may be approved by the Manager, 1801 Airport Road, 
Room 100, Wichita, Kansas 67209.
    (1) The request shall be forwarded through an appropriate FAA 
Maintenance Inspector, who may add comments and then send it to the 
Manager, Wichita Aircraft Certification Office.
    (2) Alternative methods of compliance approved in accordance 
with AD 75-23-08 R5 are not considered approved as alternative 
methods of compliance for this AD.

    Note 4: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Wichita Aircraft Certification Office.

    (l) Information related to this AD may be examined at the FAA, 
Central Region, Office of the Regional Counsel, Room 1558, 601 E. 
12th Street, Kansas City, Missouri 64106.
    (m) This amendment supersedes AD 75-23-08 R5, Amendment 39-5451.

Appendix to Docket No. 97-CE-67-AD--Visual Inspection

(a) Cleaning

    In order to properly inspect the exhaust system, components must 
be clean and free of oil, grease, etc. If required, clean as 
follows:
    (1) Spray engine exhaust components with a suitable solvent 
(such as Stoddard Solvent), allow to drain, and wipe dry with a 
clean cloth.

WARNING NEVER USE HIGHLY FLAMMABLE SOLVENTS ON ENGINE EXHAUST SYSTEMS. 
NEVER USE A WIRE BRUSH OR ABRASIVES TO CLEAN EXHAUST SYSTEMS OR MARK ON 
THE SYSTEM WITH LEAD PENCILS.

    (2) Remove the heat shields from the turbocharger in accordance 
with the heat shield removal procedures in the appropriate Cessna 
Aircraft Service Manual.
    (3) Remove shields around the exhaust bellows or slip joints, 
multi-segment ``V'' band clamps at joints, and other items that 
might hinder the inspection of the system. Removal of the ``V'' band 
clamps may not be necessary.
    (4) Using crocus cloth, polish any suspect surfaces to verify 
that no cracks or pinholes exist in the material. Replace or repair 
any part where cracks or pinholes exist.

(b) Visual Inspection of Complete System

    Note 1. Conduct this inspection when the engine is cool.

    (1) Visually inspect exhaust stacks for burned areas, cracks, 
bulges, and looseness. Make sure the attach bolts are properly 
torqued, in accordance with the appropriate Cessna Aircraft Service 
Manual.

    Note 2. During this inspection, pay special attention to the 
condition of the bellows and welded areas along the seams; the 
welded areas around the bellows; and the welded seams around the 
exhaust system components.

    (2) Visually inspect the flexible connection between the waste-
gate and overboard duct (when applicable) for cracks and security.
    (3) Visually inspect the exhaust joint springs for correct 
compression. If the joint is disturbed or if the springs are 
obviously loose or frozen, proceed with the following inspection 
(see Figure 1 of this Appendix).
    (i) Before removal of the exhaust joint springs, measure the 
installed length of each spring, and replace the springs compressed 
to less than .45 inch.
    (ii) Remove all the springs and measure the free length. Replace 
any spring having a free length of less than .57 inch.


[[Page 36312]]


    Note 3. Add AN960-10 washers under the head of the joint bolts 
as required to obtain the correct dimension. During installation, 
the joint bolts should be tightened gradually and spring length 
checked frequently to prevent over-compression of the springs.

    (iii) Reinstall the springs and measure the installed length. 
The length must be .51 inch (+.00, -.03 inch).
    (4) If installed, visually inspect the slip joint(s) for bulges 
beyond the normal manufacturing irregularities of .03 inches and/or 
cracks. If any bulges and/or cracks are present, replace the bulged 
or cracked slip joint(s). (Refer to the appropriate Cessna Aircraft 
Service Manual) (See Figure 2 of this Appendix).

(c) Inspection of the Multi-Segment ``V'' Band Clamp(s) (Between 
Engine and Turbocharger)

    (1) Using crocus cloth, clean the outer band of the multi-
segment ``V'' band clamp(s). Pay particular attention to the spot 
weld area on the clamp(s).
    (2) With the clamp(s) properly torqued, progress to the 
following actions:
    (i) Visually inspect the outer band in the area of the spot weld 
for cracks (see Figure 3 of this Appendix). If cracks are found, 
replace the clamp(s) with new multi-segment ``V'' band clamp(s).
    (ii) Visually inspect the corner radii of the clamp inner 
segments for cracks (see Figure 3 of this Appendix). This inspection 
requires careful use of artificial light and inspection mirrors.
    (iii) Visually inspect the flatness of the outer band, 
especially within 2 inches of the spot welded tabs that retain the 
T-bolt fastener. This can be done by placing a straight edge across 
the flat part of the outer band as shown in Figure 4 of this 
Appendix, then check the gap between the straight edge and the outer 
band. This gap should be less than 0.062 inch. If deformation 
exceeds the 0.062-inch limit, replace the clamp(s) with new multi-
segment clamp(s). (See Figure 3 of this Appendix). See Cessna 
maintenance manual(s) and revisions for correct installation 
procedures.
    (iv) Visually inspect the one-piece ``V'' band clamp (overboard 
exhaust to turbocharger) with a light and mirror, in the area of the 
clamp surfaces adjacent to the intersection of the ``V'' apex and 
bolt clips, and the entire length of the ``V'' apex of the clamp for 
signs of cracks or fractures. If cracks or fractures are visible, 
replace the clamp (see Figure 5 of this Appendix). See Cessna 
service manual(s) and revisions for correct installation procedures

BILLING CODE 4910-13-U

[[Page 36313]]

[GRAPHIC] [TIFF OMITTED] TP06JY99.006



[[Page 36314]]

[GRAPHIC] [TIFF OMITTED] TP06JY99.007



[[Page 36315]]

[GRAPHIC] [TIFF OMITTED] TP06JY99.008



[[Page 36316]]

[GRAPHIC] [TIFF OMITTED] TP06JY99.009



[[Page 36317]]

[GRAPHIC] [TIFF OMITTED] TP06JY99.010



BILLING CODE 4910-13-C

[[Page 36318]]

Inspection of the Exhaust System AFT of the Slip Joints

    (a) Remove all top and bottom engine cowlings, as well as the 
under-nacelle inspection panels (on aircraft so-equipped). Remove 
the nacelle-mounted induction air filter canister, slip-joint heat 
shields, turbocharger heat shields, and any other readily-removable 
components that facilitate a better view of the exhaust system aft 
of the slip joints.
    (b) Visually inspect each elbow pipe that runs from the slip 
joint to the wye duct. Carefully inspect the hard-to-see areas where 
the manifold passes through the canted bulkhead, beneath the clamp-
on heat shields, and around the flange and V-band clamp, where it 
joins the wye. Use a flashlight and mirror to inspect the areas that 
cannot be seen directly.
    (1) Look for evidence of exhaust stains, bulges, cracks, or 
pinholes.
    (2) Exhaust stains or evidence of heat-induced corrosion on any 
portion of the engine mount beams or canted bulkhead should be 
grounds for removing the elbow pipe for closer inspection.
    (3) Inspect for cracks, bulges, pinholes, or corrosion on the 
elbow (manifold) pipe, and if any of this damage is found, replace 
the elbow pipe.
    (c) Visually inspect each wye duct beneath the turbo charger for 
leakage, stains, cracks, or pinholes, and, if damaged, repair or 
replace. Carefully inspect the hard-to-see area between the duct and 
firewall.
    (1) Carefully inspect the turbo-charger and waste-gate flanges 
and welded seams between the ducts and the firewall for evidence of 
exhaust stains on the wye or the firewall, bulges, cracks, or 
pinholes.
    (2) If exhaust stains, bulges, cracks or pinholes are found, 
repair or replace the damaged part.

Pressure Test

    (a) Pressurize the exhaust system with air regulated to 20 PSI 
or below.
    (b) Apply this air pressure to the tailpipe. Fabricate shop 
fixtures as required to accomplish this.
    (c) Seal off the waste-gate pipe.
    (d) Check the tailpipe, elbow pipes and the wye duct for leaks 
by spraying leak check fluid (bubbling) on these parts and looking 
for the appearance of bubbles. Some air leakage is normal at the 
joints and flanges, but none should be seen anywhere else.
    (e) Pay special attention to any weld repairs, and various hard-
to-see areas described previously.
    (f) If the tailpipes, elbow pipes, or the wye ducts fail the 
pressure test, repair or replace the distressed component.

    Issued in Kansas City, Missouri, on June 25, 1999.
Michael Gallagher,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-16752 Filed 7-2-99; 8:45 am]
BILLING CODE 4910-13-U