DC-10 Undifferentiated or Other Model
Situational Awareness; Communication Breakdown; Confusion
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft Aircraft Damaged; General Maintenance Action
Procedure; Aircraft; Company Policy; Human Factors
Line Maintenance submitted an Engineering Request (ER) issued in August 2013; requesting approval for minor damage to a Landing Gear Control cable feed-thru seal; primarily due to parts not being available. I reviewed the damage seal request and determined that seal; Part Number (P/N) AEH7038-501; was installed per Service Bulletin (SB) DC10-27A0237; which was the subject of Airworthiness Directive (AD) 2008-11-14. The AD required replacement of the P/N AEH7038-1 Seal with the P/N AEH7038-501 Seal as a part of the AD Terminating Action. Maintenance confirmed that the P/N AEH7038-501 Seal was installed; and reported that the only seal damage was what existed at the lower; un-pressurized seal side; where the grommet was secured within the seal; as stated in the ER. After reviewing the SB; AD and [Aircraft] drawings; I determined that the modified seal design changes; implemented by the AD; were only applicable to the upper pressurized side of the AEH7038-501 Seal. The reported seal damage:1) was not in the area affected by the AD; 2) did not alter the function or design changes made by the AD; and 3) would be classified as Minor Repair damage. It was also noted that as a result of the longer grommet used on the AEH7038-501 Seal; the grommet retention was improved due to the larger interference fit area between the seal Inside Diameter (I.D.) and the grommet Outside Diameter (O.D.). Based on the above factors and my analysis of the data; I issued the Engineering Authorization (EA) and approving the seal damage as being acceptable; as is; for continued use; and implemented the EA Follow-on Checks and Terminating Action steps. Our Air Carrier Policy requires that EAs that affect ADs are identified in the EA and reviewed by an Auditor; so I contacted Auditor Mr. X; the assigned on-call representative and informed him that I would be issuing an EA that approved the damaged seal condition for continued use as is. He reviewed the EA and released it within the one hour assigned by company policy for Auditor approval of company EAs. Approximately five days later; I received a message from Mr. X wanting me to answer four questions regarding the EA; the primary points of which had to do with what supporting approvals or documents did I use to approve the seal damage. I replied to the initial message; and the next day he sent me the following message: 'Here's the big issue: The Auditor wants to see approval from Boeing or the FAA that continued use of the damaged seal is acceptable by the Manufacturer or FAA. Remember this is an AD and your assessment that the seal is serviceable must be approved/supported; along with the tracking criteria (if the damaged seal is acceptable); by an FAA Designee. The aircraft Manufacturer should be contacted requesting a possible Temporary Repair or Approval of your request for continue service with a damaged seal.'  My initial response to the Auditor's statement that approval from the FAA or Boeing was required to permit the seal damage to continue in service; was to discuss the matter with the Manager of Structures Engineering and two other Structures Engineers. We all agreed that the damage was minor and should have been within Engineering's authority to approve an EA. Nevertheless; and without any direction to the contrary; we agreed to obtain the Manufacturer's approval as requested. I submitted a Manufacturer's request for approval of the seal condition; as approved by my EA. The aircraft Manufacturer did not approve the condition and stated in their written reply that the seal must be replaced before further flight. However; the Manufacturer had not even looked at the seal damage. Following this; I discussed this matter with the Manager of Structures and the other two Engineers; one of which was very familiar with the AD; as it was addressed by his group when he was the Manager of Structures Engineering. He agreed that Engineering has the authority to approve minor repairs and alterations; but questioned our ability to implement minor repairs and alterations on an AD installed parts. He did think I should forward the issue to upper Management for resolution; which I immediately did by informing our Senior Manager; Mr.Y. At this point; the issue was to be addressed with the FAA. Our Air Carrier's General Maintenance Manual (GMM) states that 'As described in FAA Advisory Circular No. 120-77; only major changes to FAA-approved technical data require additional FAA approval. Once an AD is implemented; it becomes part of the aircraft's approved technical data. As such; it now falls under the FAA Operator Guidelines for approval of Major or Minor Repairs and Alterations. Following this logic; per our GMM; the seal damage is classified as a Minor repair to a Major Repair or Alteration; which; per the GMM Repair/Alteration Logic Diagram; would place you in Block 13; Aircraft Engineering acquires or develops approved data. There is a conflict at this point; which is that: 'approved data' is actually referring to FAA Approved Data. To state that Aircraft Engineering develops approved data for Major repairs is misleading. All approved data must be FAA Approved Data. However; this GMM section does not address Minor repairs to Major Repairs and Alterations; which; per the GMM; does not require FAA approval. After discussing this matter with the aforementioned individuals; except for one of the Engineers; it was the consensus view that Engineering does have the authority to approve Minor Repairs and Alterations; but in the case of an AD installed part; it should be clarified that Engineering's minor approval authority is limited in that they:1) may not effect or alter the modification added or incorporated by the AD; and 2) may not effect or alter the functions incorporated by the AD. The response by Engineering to ask the aircraft Manufacturer for approval of the seal damage; as requested by the Auditor; was a knee-jerk reaction and a mistake. It should have been addressed by a face to face meeting between the knowledgeable individuals in Engineering and the Auditor; to discuss why our Air Carrier Engineering does; or does not; have the authority to approve minor repairs on AD installed parts. After reviewing the GMM and Advisory Circulars (A/C); it is was the consensus view that Engineering has the authority to approve minor repairs to AD installed parts; but there needs to be clarification in the GMM that restricts our authority so that we do not approve minor damage to AD affected areas that would affect the modifications or the functions incorporated by an AD. Misunderstanding of Aircraft Engineering's authority to approve Minor Repairs and Alterations to FAA approved technical data; which includes AD installed parts. GMM section for Major / Minor Repair and Alteration Classification procedures needs to be further clarified to identify that Aircraft Engineering has the authority to approve minor repairs and alterations to FAA- approved technical data; which includes minor repairs and alterations to AD installed components; provided that they: 1) Do not effect or alter the modification added or incorporated by the AD; and 2) Do not effect or alter the functions incorporated by the AD.
An Air Carrier Engineer describes his Logic/Analysis as to why he had the authority to issue an Engineering Authorization (E/A) for a Minor Repair he had approved to a Landing Gear Control cable feed-thru pressure seal on a DC-10 aircraft. The seal was subject to Airworthiness Directive (A/D) 2008-11-14 that referenced Service Bulletin (S/B) DC10-27A0237.