AD 91-07-15

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AD Number:
91-07-15
Document Type:
AD Final Rules
Docket Number:
90-NM-242-AD
Subject Heading:
Airworthiness Directives; McDONNELL DOUGLAS DC-10-15, -30, -30F, and KC-10A (Military) Series Airplanes
Subject:
Engine Mount Truss Assembly
Status:
Current
Citation:
This information is not available.
Citation Publish Date:
Effective Date:
05/10/1991
Make:
The Boeing Company
Model:
DC-10-15 | DC-10-30 | DC-10-30F (KC-10A, KDC-10)
Product Type:
Aircraft
Product Subtype:
Large Airplane
Affected AD:
Superseded AD:
Affected By:
Superseded By:
Service/Office:
Office of Primary Responsibility:
CFR Part Reference:
Part 39
Comments:
AIRWORTHINESS DIRECTIVES FINAL RULES: 91-07-15
CITATION:   This information is not available.

PAGE NUMBER:  

DOCKET NUMBER:   90-NM-242-AD

AMENDMENT:   39-6961

AD NUMBER:   91-07-15

SUBJECT HEADING:   Airworthiness Directives; McDONNELL DOUGLAS DC-10-15, -30, -30F, and KC-10A (Military) Series Airplanes

ACTION:  

SUMMARY:  

DATES:   Effective May 10, 1991.

ADDRESSES:  

FOR FURTHER INFORMATION CONTACT:  

SUPPLEMENTARY INFORMATION:  

REGULATORY TEXT:  
91-07-15 McDONNELL DOUGLAS: Amendment 39-6961. Docket No. 90-NM-242-AD.

Applicability: All Model DC-10-15, -30, -30F, and KC-10A (Military) series airplanes, certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent the failure of the engine forward mount truss assembly on pylons 1 and 3, accomplish the following:

A. Prior to the accumulation of 9,000 landings or 30,000 flight hours, whichever occurs first, or within 20 days after June 22, 1989 (the effective date of Amendment 39-6235, AD 89-13-01), whichever occurs later, conduct an eddy current inspection of the engine forward mount truss assembly on pylons 1 and 3, in accordance with Paragraph 2, "Accomplishment Instructions," of McDonnell Douglas Alert Service Bulletin No. A54-99, Revision 1, dated March 31, 1989; or Revision 2, dated July 17, 1990 (hereafter referred to as A54-99). Conduct subsequent inspections in accordance with the subparagraph applicable to the condition detected.

1. If no crack indications are found in either horizontal flange, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 2,000 landings or 6,000 flight hours, whichever occurs first.

2. If a single crack indication in one bolt hole of the horizontal flange is found with no crack indication extending out from under the AUB7013-1 angle, and there are no crack indications in the opposite fitting, accomplish the following:

a. Conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 500 flight hours;

and

b. Prior to the accumulation of 500 landings or 2,000 flight hours, whichever occurs first, after the initial detection of a crack, accomplish one of the following:

(1) Install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-502 truss fitting, as applicable, in accordance with A54-99. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 1,000 flight hours to monitor crack propagation;

or

(2) Enlarge the diameter of the fastener hole to remove the crack indication and install new fasteners in accordance with A54-99.

(a) If the crack indication is eliminated, conduct repetitive eddy current inspections in accordance with A54-99 of the repaired truss fitting for cracks in the forward horizontal flange attaching bolt holes at intervals not to exceed 1,500 landings or 4,500 flight hours, whichever occurs first.

(b) If the crack indication still exists in the truss fitting after enlarging the fastener hole, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. strap on the AUB7000-502 truss fitting, as applicable, in accordance with A54-99. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 1,000 flight hours to monitor crack propagation.

3. If a single crack indication in one bolt hole is found in the horizontal flange with the crack extending out from under the AUB7013-1 angle, but not beyond the tangent point of the fillet radius to the vertical flange, as shown on Figure 2 (Condition III) of A54-99, and there are no crack indications in the opposite fitting, accomplish the following:

a. Prior to further flight, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-502 truss fitting, as applicable, in accordance with A54-99;

and

b. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 250 flight hours to monitor crack propagation.

4. If multiple crack indications in the bolt holes are found in the horizontal flange, with no crack extending out from under the AUB7013-1 angle, and there are no crack indications in the opposite fitting, accomplish one of the following:

a. Prior to further flight, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-502 truss fitting, as applicable. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 1,000 flight hours to monitor crack propagation;

or

b. Prior to further flight, enlarge the diameter of the fastener holes to remove the crack indications and install new fasteners in accordance with A54-99.

(1) If the crack indications are eliminated, repetitively inspect the repaired truss fitting for cracks in the forward horizontal flange attaching bolt holes in accordance with A54-99 at intervals not to exceed 1,500 landings or 4,500 flight hours, whichever occurs first.

(2) If the crack indications still exist in the truss fitting after enlarging the fastener holes, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the AUB7000-501 truss fitting, or install SR10540003-4 Rev A. or B. strap on the AUB7000-502 truss fitting, as applicable. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 1,000 flight hours to monitor crack propagation.

5. If multiple crack indications in the bolt holes are found in the horizontal flange with a crack extending out from under the AUB7013-1 angle, but not progressing beyond the tangent point of the fillet radius to the vertical flange, as shown in Figure 2 (Condition V) of A54-99, and there are no crack indications in the opposite fitting, accomplish the following:

a. Prior to further flight, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-502 truss fitting, as applicable, in accordance with A54-99;

and

b. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 250 flight hours to monitor crack propagation.

6. If a crack is found to have extended out from under the AUB7013-1 angle in the horizontal flange, through the fillet radius into the vertical flange, as shown in Figure 2 (Condition VI) of A54-99: Prior to further flight, replace the cracked/repaired truss fitting with a new fitting and continue inspections in accordance with this AD.

7. If cracks are found in both horizontal flanges of the AUB7000 truss fittings, accomplish the following:

a. Prior to further flight, replace at least one of the cracked/repaired truss fittings with a new fitting and continue inspections in accordance with the subparagraph applicable to the condition remaining;

or

b. Prior to further flight, enlarge the diameter of the fastener holes to remove the crack indications; install new fasteners in accordance with A54-99; and accomplish the following, as appropriate:

(1) If the crack indications are eliminated, repetitively inspect the repaired truss fitting for cracks in the forward horizontal flange attaching bolt holes in accordance with A54-99 at intervals not to exceed 1,500 landings or 4,500 flight hours, whichever occurs first.

(2) If the crack indications still exist in a single truss fitting after enlarging the fastener holes, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. strap on the AUB7000-502 truss fitting, as applicable, in accordance with A54-99. After installation of the strap, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 1,000 flight hours to monitor crack propagation.

(3) If crack indications still exist in both fittings after enlarging fastener holes, install SR10540003-3 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-501 truss fitting, and install SR10540003-4 Rev. A. or B. strap on the horizontal flange of the cracked AUB7000-502 truss fitting, in accordance with A54-99;

(a) After installation of the straps, conduct repetitive eddy current inspections in accordance with A54-99 at intervals not to exceed 500 flight hours to monitor crack propagation.

(b) At the later of the times specified below, replace at least one of the truss fittings in accordance with A54-99:

(i) Within 1,200 landings or 3,600 flight hours, whichever occurs first,

or

(ii) Within one year after the effective date of this AD.

B. At the time of the next inspection required by paragraph A.1. through A.7. of this AD following the effective date of this AD, conduct an eddy current inspection of the vertical flange of the AUB7000-501 and/or AUB7000-502 truss fitting, as applicable, in accordance with the "Accomplishment Instructions" of McDonnell Douglas Alert Service Bulletin A54-103, dated March 7, 1990 (hereafter referred to as A54-103).

C. As a result of the inspections of the vertical flange required by paragraph B. of this AD, accomplish the following. Conduct subsequent inspections in accordance with the subparagraph applicable to the condition detected.

1. If no cracks are found in the vertical flange, conduct repetitive eddy current inspections of the vertical flange in accordance with A54-103 concurrently with each inspection required by paragraph A.1. through A.7. of this AD.

2. If crack indication(s) are found in the vertical flange, with no crack indication extending through the fillet radius into the horizontal flange and a crack indication exists in the horizontal flange, accomplish the following:

a. Prior to further flight, install SR10540003-3 Rev. A. or B. and SR10540003-5 straps on the cracked AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. and SR10540003-6 on the cracked AUB7000-502 truss fitting, as applicable, in accordance with A54-103;

and

b. Conduct repetitive eddy current inspections in accordance with A54-103 at intervals not to exceed 250 flight hours to monitor the crack propagation.

3. If crack indication(s) are found in the vertical flange, with no crack indication extending through the fillet radius into the horizontal flange; and if no crack indication exists in the horizontal flange; accomplish the following:

a. Prior to further flight, install SR10540003-3 Rev. A. or B. and SR10540003-5 straps on the cracked AUB7000-501 truss fitting, or install SR10540003-4 Rev. A. or B. and SR10540003-6 on the cracked AUB7000-502 truss fitting, as applicable, in accordance with A54-103;

and

b. Conduct repetitive eddy current inspections in accordance with A54-103 at intervals not to exceed 1,000 flight hours to monitor crack propagation.

4. If a crack in the vertical flange is found to have extended through the fillet radius into the horizontal flange: Prior to further flight, replace the cracked/repaired truss fitting with a new fitting and continue inspections in accordance with this AD.

D. Except as in provided in paragraph A.7, after the installation of a repair strap on the P/N AUB7000-501, or -502 truss fitting, replace the truss fitting in accordance with A54-99 prior to the later of the times specified in subparagraphs D.1. and D.2., below:

1. Prior to the accumulation of 2,400 landings or 7,200 flight hours, whichever occurs first;

or

2. Within 2 years.

E. Replace the P/Ns AUB7000-501 and -502 truss fittings with P/Ns AUB7000-503 and -504 in accordance with A54-99, at the later of the times specified in subparagraphs E.1. and E.2., below. Such replacement constitutes terminating action for the repetitive eddy current inspections required by the AD.

1. Prior to the accumulation of 9,000 landings or 30,000 flight hours, whichever occurs first; or

2. Within 6 years after the effective date of this AD.

F. An alternative method of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Los Angeles Aircraft Certification Office (ACO), FAA, Transport Airplane Directorate.

NOTE: The request should be forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Los Angeles ACO.

G. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD.

All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to McDonnell Douglas Corporation, P. O. Box 1771, Long Beach, California 90846-0001, Attention: Business Unit Manager, Technical Publications, C1-HDR (54-60). These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington, or Los Angeles Aircraft Certification Office, 3229 East Spring Street, Long Beach, California.

Airworthiness Directive 91-07-15 supersedes AD 90-13-03, Amendment 39-6634 which superseded 89-13-01 (Amendment 39-6235), and 89-05-53 (Amendment 39-6189).

This amendment (39-6961, AD 91-07-15) becomes effective on May 10, 1991.


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