[Federal Register Volume 61, Number 94 (Tuesday, May 14, 1996)]
[Rules and Regulations]
[Pages 24220-24222]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-11959]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 96-SW-02-AD; Amendment 39-9615; AD 96-10-09]
RIN 2120-AA64


Airworthiness Directives; McDonnell Douglas Helicopter Systems 
Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, 
and 500N Helicopters

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that 
is applicable to McDonnell Douglas Helicopter Systems (MDHS) Model 369, 
369A, 369D, 369E, 369F, 369FF, 369H, 369HE, 369HM, 369HS, and 500N 
helicopters. This action requires initial and repetitive inspections of 
each main rotor blade (blade) root for either cracks or paint and 
sealant cracking or separation between the lower surface root end 
fitting and the doubler. This amendment is prompted by one accident in 
which a blade separated from the helicopter, as well as eight other 
reports of cracked blades. The actions specified in this AD are 
intended to prevent failure of a blade resulting in separation of the 
blade and subsequent loss of control of the helicopter.

DATES: Effective May 29, 1996.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of 15 days after the date of publication in the Federal Register.
    Comments for inclusion in the Rules Docket must be received on or 
before July 15, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Office of the Assistant Chief Counsel, Attention: 
Rules Docket No. 96-SW-02-AD, 2601 Meacham Blvd., Room 663, Fort Worth, 
Texas 76137.
    The service information referenced in this AD may be obtained from 
MDHS, Technical Publications, Bldg. 530/B111, 5000 E. McDowell Rd., 
Mesa, Arizona 85215-9797. This information may be examined at the FAA, 
Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas 76137; or at the Office of the Federal Register, 800 
North Capitol Street NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Mr. John Cecil, Aerospace Engineer, 
ANM-120L, Los Angeles Aircraft Certification Office, Northwest Mountain 
Region, 3960 Paramount Blvd., Lakewood, California, telephone (310) 
627-5322, fax (310) 627-5210.

SUPPLEMENTARY INFORMATION: This amendment adopts a new AD that is 
applicable to MDHS Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 
369HE, 369HM, 369HS, and 500N helicopters. One accident occurred in 
August 1995 in which one blade separated from the rotor system while 
the helicopter was on the ground. Additionally, there were eight 
reports of blade cracking prior to the one accident, all of which were 
discovered during either routine inspections or inspections resulting 
from reported abnormal vibrations. Subsequent investigations revealed 
that bonding separation occurred between the lower surface root end 
fitting and the doubler. This condition, if not corrected, could result 
in failure of a blade resulting in separation of the blade and 
subsequent loss of control of the helicopter.

[[Page 24221]]

    The FAA has reviewed McDonnell Douglas Helicopter Systems Service 
Information Notice No. HN-239, DN-188, EN-81, FN-67, and NN-008, dated 
October 27, 1995, which describes procedures for a one-time visual 
inspection of the blade root end for chordwise cracking and paint or 
sealant cracking between the lower surface root end fitting and the 
doubler, and then repetitive inspections at intervals of 100 hours 
time-in-service (TIS).
    Since an unsafe condition has been identified that it is likely to 
exist or develop on other MDHS Model 369, 369A, 369D, 369E, 369F, 
369FF, 369H, 369HE, 369HM, 369HS, and 500N helicopters of the same type 
design, this AD is being issued to prevent failure of a blade at the 
root end due to fatigue cracking that initiates at the outboard bolt 
hole and usually travels in a chordwise direction. This AD requires, 
within 10 hours TIS after the effective date of this AD, a one-time 
visual inspection of each blade root end near the doubler paying 
particular attention to chordwise cracks and paint or sealant cracking 
or separation between the lower surface root end fitting and the 
doubler. Additionally, this AD requires repetitive visual inspections 
of each blade, at intervals not to exceed 100 hours TIS, for bond 
separation between the lower surface root end fitting and doubler 
paying particular attention to chordwise cracks. The actions are 
required to be accomplished in accordance with the service information 
notice described previously.
    Due to the critical need to ensure the integrity of the main rotor 
system, and to comply with the requirements of this AD within 10 hours 
TIS, this rule must be issued immediately to correct an unsafe 
condition in the affected helicopters.
    Since a situation exists that requires the immediate adoption of 
this regulation, it is found that notice and opportunity for prior 
public comment hereon are impracticable, and that good cause exists for 
making this amendment effective in less than 30 days.

Comments Invited

    Although this action is in the form of a final rule that involves 
requirements affecting flight safety and, thus, was not preceded by 
notice and an opportunity for public comment, comments are invited on 
this rule. Interested persons are invited to comment on this 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 under the caption ADDRESSES. All 
communications received on or before the closing date for comments will 
be considered, and this rule may be amended in light of the comments 
received. Factual information that supports the commenter's ideas and 
suggestions is extremely helpful in evaluating the effectiveness of the 
AD action and determining whether additional rulemaking action would be 
needed.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the rule that might 
suggest a need to modify the 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 
AD will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this rule must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket No. 96-SW-02-AD.'' The postcard will be date stamped and 
returned to the commenter.
    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.
    The FAA has determined that this regulation is an emergency 
regulation that must be issued immediately to correct an unsafe 
condition in aircraft, and that it is not a ``significant regulatory 
action'' under Executive Order 12866. It has been determined further 
that this action involves an emergency regulation under DOT Regulatory 
Policies and Procedures (44 FR 11034, February 26, 1979). If it is 
determined that this emergency regulation otherwise would be 
significant under DOT Regulatory Policies and Procedures, a final 
regulatory evaluation will be prepared and placed in the Rules Docket. 
A copy of it, if filed, 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding a new airworthiness directive 
to read as follows:

AD 96-10-09  McDonnell Douglas Helicopter Systems: Amendment 39-
9615. Docket No. 96-SW-02-AD.

    Applicability: Model 369, 369A, 369D, 369E, 369F, 369FF, 369H, 
369HE, 369HM, 369HS, and 500N helicopters, certificated in any 
category.

    Note 1: This AD applies to each helicopter 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 helicopters that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must use the authority 
provided in paragraph (c) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition, or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any helicopter from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of a main rotor blade (blade) resulting in 
separation of the blade and subsequent loss of control of the 
helicopter, accomplish the following:
    (a) Within 10 hours time-in-service (TIS) after the effective 
date of this AD, perform a visual inspection of each blade root end 
for cracking and paint or sealant cracking, paying particular 
attention to chordwise cracking, and for separation between the 
lower surface root end fitting and doubler, in accordance with Part 
I of the Accomplishment Instructions of McDonnell Douglas Helicopter 
Systems Service Information Notice (SIN) HN-239, DN-188, EN-81, FN-
67, and NN-008, dated October 27, 1995. If any blade crack is noted, 
before further flight, remove the blade and replace it with an 
airworthy blade. If paint or sealant cracking or separation is 
noted, accomplish the inspection in paragraph 3E of Part II of the 
Accomplishment Instructions of SIN HN-239, DN-188, EN-81, FN-67, and 
NN-008, dated October 27, 1995, using a piece of Mylar/viewfoil that 
is no thicker than .004-inch and that is cut to a size between 0.9 
inch

[[Page 24222]]

and 1.1 inches wide and between 3.9 inches and 4.1 inches long. If 
any corner of the Mylar can be inserted between the lower surface 
root end fitting and doubler surface to a depth of 0.1 inch or 
greater, remove the blade from service and replace it with an 
airworthy blade.
    (b) Thereafter, at intervals not to exceed 100 hours TIS, remove 
the blades and inspect for cracking, paying particular attention to 
chordwise cracking, and separation between the lower surface root 
end fitting and doubler in accordance with Part II of the 
Accomplishment Instructions of McDonnell Douglas Helicopter Systems 
SIN HN-239, DN-188, EN-81, FN-67, and NN-008, dated October 27, 
1995. If missing or cracked adhesive or paint is detected at the 
lower surface root end fitting to doubler bonding line, accomplish 
the inspection in paragraph 3E of Part II of the Accomplishment 
Instructions of SIN HN-239, DN-188, EN-81, FN-67, and NN-008, dated 
October 27, 1995 using a piece of Mylar/viewfoil that is no thicker 
than .004-inch that is cut to a size between 0.9 inch and 1.1 inches 
wide and between 3.9 inches and 4.1 inches long. If any corner of 
the Mylar can be inserted between the lower surface root end fitting 
and doubler surface to a depth of 0.1 inch or greater, remove the 
blade from service and replace it with an airworthy blade.
    (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, FAA. Operators shall submit their requests through an FAA 
Principal Maintenance Inspector, who may concur or comment and then 
send it to the Manager, Los Angeles Aircraft Certification Office.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Los Angeles Aircraft Certification Office.

    (d) Special flight permits will not be issued.
    (e) The inspections shall be done in accordance with McDonnell 
Douglas Helicopter Systems Service Information Notice (SIN) HN-239, 
DN-188, EN-81, FN-67, and NN-008, dated October 27, 1995. 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 McDonnell Douglas Helicopter 
Systems, Technical Publications, Bldg. 530/B111, 5000 E. McDowell 
Rd., Mesa, Arizona 85215-9797. Copies may be inspected at the FAA, 
Office of the Assistant Chief Counsel, 2601 Meacham Blvd., Room 663, 
Fort Worth, Texas; or at the Office of the Federal Register, 800 
North Capitol Street, NW., suite 700, Washington, DC.
    (f) This amendment becomes effective May 29, 1996.

    Issued in Fort Worth, Texas, on May 2, 1996.
Eric Bries,
Acting Manager, Rotorcraft Directorate, Aircraft Certification Service.
[FR Doc. 96-11959 Filed 5-13-96; 8:45 am]
BILLING CODE 4910-13-U