Flight Crew Instrument; Flight Crew Commercial; Maintenance Airframe; Maintenance Powerplant
Maintenance Lead Technician 0.5; Maintenance Technician 2
Communication Breakdown; Troubleshooting
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural MEL / CDL
General Flight Cancelled / Delayed; General Maintenance Action; General Work Refused
Procedure; Logbook Entry; Aircraft; Staffing
My Recommendation: Because there is what I believe to be a low but uncertain chance that the primary pressure vessel of the Aircraft X has a current active failure; the aircraft should be immediately grounded; and an investigation be initiated into whether this issue is just a classification and engineering oversight; or indeed a failure to the aircraft's primary structure. Aircraft X (Boeing-767-300) is potentially operating on an inapplicable airworthiness sign off and may fly (already has flown) with a possible serious defect to the aircraft's primary structure (pressure vessel). Aircraft X arrived at ZZZ station December 2020. Upon arrival the following defect was found and recorded into the maintenance log book:Discrepancy: Undocumented Speed tape found concealing stripped & unsecured mounting screw to extruded Main Cargo Door (MCD) Manual Vent Door Drive (Pressure Vessel) cover panel.I notified Maintenance Control of the defect and submitted via email a proposal for a temp repair utilizing non-standard substitution parts available on-hand at our station that I hoped would allow for a timely repair keeping the aircraft on scheduled revenue flights despite the need for an Engineering Order (EO) and additional authorizations. After an appropriate time; an outline of maintenance action to be completed was submitted to our station for a yet unapproved EO numbered: XXXXXXXX; that was a substantial deviation from my own earlier proposed temp repair. This EO after performing a Detailed Visual Inspection (DVI) merely called for reattaching the panel in place with RTV-106 sealant; no hardware; and a covering of multiple layers of aluminum speed tape. Knowing that an external application of tape over a hole in the primary pressure vessel of an aircraft did not meet the basic criteria for acceptable maintenance standards; I contacted maintenance Control to inform them that we (aircraft technicians under my purview) at ZZZ would not be able to comply with the EO maintenance instructions as they were currently written because of the safety implications.After expressing my unwillingness to press forward with the draft EO I began receiving pressuring communications from various maintenance controllers; maintenance duty managers; and Company management; saying everything from 'just do it;' to 'it'll be fine.' Additionally; it was overheard in background talk on more than one phone call with maintenance controllers that they did not believe the panel in question was actually a primary pressure vessel fitting as I had asserted in multiple emails and phone conversations; and was merely a weather seal. Worried that I had somehow made an egregious mistake about the panel in-fact being a pressure hull seal; I enlisted both additional night shift mechanics to assist with a cabin pressurization leak check (referencing AMM 05-51-24-782-001) with the damaged MCD Manual Drive cover panel removed. As I operated the cabin pressure manually; utilizing APU bleed source; the two assisting technicians reported a strong; unrestricted flow of air emanating from the uncovered hole; while I was observing only 1 PSI indicated differential cabin pressure. Believing that this observation adequately supported my previous assertation; I terminated the test; returned the aircraft to its previous configuration; and felt confident that my continued refusal to repair the aircraft as outlined in the draft EO to be a safe and correct judgment call.The scheduled departure of the aircraft was altered from XA:15z to XE:00z. At XB:16z I received an email asking me to 'please call In to Maintenance Control to advise on current status of approved EO compliance;' (no approved EO had been received or transmitted to anyone at ZZZ station). Given the ongoing pressure from phone calls and condescending emails to comply with an EO I had yet to see; I advised [the] maintenance controllers that I would not be complying with the EO and to direct all future communications to be in writing. I then suggested at that point that they 'just AOG (aircraft on ground) ship the required parts necessary to return this defect to its original condition;' with the observation 'that the original undocumented speed tape repair has already been proven to fail;' as my own justification for non-compliance with an EO that called for doing the same thing; only with more tape.At XD:50z we received the first approved copy of the EO XXXXXXXX via email from the Maintenance Manager; which upon review was consistent with the advised sealant and tape repair already rejected. The scheduled aircraft departure was once again pushed back to XG:00z; well after the scheduled arrival of the oncoming maintenance day shift. At XE:15z I received a phone call from my Company Regional Manager asking me why I was not complying with the EO and then; regarding taping over a hole in the pressure vessel; to 'explain how this is a safety concern?' After briefly elaborating to him about how the loss of cabin pressure makes flight crews go to sleep and planes to become lawn-darts; he said that I would 'have coverage in terms of liability because the engineer signed off on three layers of speed tape.' After mutually disagreeing; he proceeded to switch the subject to asking me which maintenance technicians were coming in on day shift; then; seeming unsatisfied; continued to ask me about the status of other technicians not scheduled for shift. Several minutes after hanging up; another call was received from a subordinate technician; not scheduled to come in; inquiring as to what was going on and why the Regional Manager was asking him to come into work on his weekend and 'override' us. At the advice of another technician overhearing the conversations; I took a written note of the above quotes from the calls.With continued inquiries for resolution on the aircraft; the oncoming day shift Lead informed Maintenance Control that the EO was still unworkable as it was and reiterated that the original temp repair proposal forwarded to Maintenance Control that included substituted hardware installation would be a fix deemed acceptable and believed conforming with standard practices that we would still be willing to sign off on. Giving in; the Maintenance Controller agreed to get the hardware installation added to a revised version of the EO along with an additional step for a cabin pressurization check that the day shift Lead smartly felt necessary for repairs performed on the pressurized structure of an aircraft. With assurances that the revised EO would include the agreed upon amendments; the day shift Lead and myself expedited the repair to the aircraft in an effort to make the scheduled departure pending timely receipt of the revised EO. The cabin pressure leak check of the repair was then successfully accomplished with only a small movement observed in the repair at a peak indicated differential pressure of 4.5 PSI; and no leaks or excessive loss rates noted. Upon departing the aircraft to accomplish paperwork closeout we were greeted by the oncoming flight crew; who had apparently been kept apprised of the ongoing situation and wanted to personally thank us for looking out for their safety.At XF:18z we received the approved EO XXXXXXXX Revision 1. Required paperwork was completed; signed log pages were sent; flight crew was briefed; and the aircraft was returned to green status at XG:10z. The aircraft subsequently blocked out of the gate at XG:39z for a delay from scheduled departure of 39 minutes. Why is this a safety concern? Upon later realization and review; I have found several possible deviations to Federal Aviation Regulations (FARs); the airline General Maintenance Manual; and uncertainty to the validity of the accomplished repair that should be investigated immediately as it may represent a serious safety issue to the aircraft. Having been so narrowly focused on getting the point across to the necessary parties involved in the tribulations of Dec Xth that the damaged part was indeed part of the pressure vessel of the aircraft and that a workable repair would have to be tailored to the additional physics involved with that part of the structure; I failed to realize the broader implications of what a repair to the pressurized structure of an aircraft entailed in terms of adherence to regulations; maintenance policy; and accepted practices. The FARs define 'Primary Structure: is that structure which carries flight; ground; or pressurization loads; and whose failure would reduce the structural integrity of the airplane.' Even though steps were added to Revision 1 of the EO to conform the repair to acceptable practices 'equal to its original or properly altered condition;' because the installation hardware was a reasonably close approximation of the original parts; the additional step of adding three layers of overlapping speed tape is in direct contradiction to the airline General Maintenance Manual policy for its use:          -HIGH SPEED ALUMINUM TAPE-          High speed tape is a convenient material for use as an interim repair for          non-structural materials. Under no circumstances will it be used on primary          aircraft structure. A Log Book entry is required when high speed tape is           applied unless instructed to do so by an EO with DER approval.Under this policy; the use of speed tape in this manner is strictly forbidden and forgiveness when it comes to doing the maintenance under the provision of an EO only absolves the requirement of a log book entry for its use. However; even though agreement was made in Revision 1 of the EO for addition of attachment hardware and an added cabin pressurization leak check; the EO creator did not alter the original classification of the repair to acknowledge that the repair was in-fact being accomplished on an aircraft primary structure:          'The Main Deck Cargo Door Manual Vent Door Drive Cover is considered secondary          structure. The time limited repair per this EO is minor; and the temporary           repair per Part 1 does not affect the fit; form or function of the skin.'I would imagine this to be an oversight; and if it is; then an additional revision needs to be made which would at a minimum alter the category of the defect deferral and its associated time-limited re-inspections and permanent repair due date/cycles. If this is not an oversight; however; as this EO has been twice over reviewed and approved; and the MCD Manual Vent Door Drive Cover is indeed a secondary structure; then the original investigative cabin pressure leak test failed for a reason other than indicated (i.e. there is an existing failure of the primary pressure vessel somewhere internal to the Main Cargo Door). Which would in turn mean that a damaged secondary structure is now fulfilling the function of a primary structure pressure seal. I do not believe this to be the case; but; as the MCD is a modification from the original aircraft structure; the existing reference material available for my use to confirm the hypothesis that the cover plate is indeed a primary structure component is vague and uncertain. Tech Engineering likely has additional references not available at a line station that could perhaps shed light on the issue.Since issuing equivalent versions of the above safety report to both Airline and Company on [the next day]; Aircraft X has remained on a regular flight schedule with recurrent re-inspects per Part 2 of EO XXXXXXXX Rev 1; until receiving Part 3 Permanent Repair [4 days later]. I can currently find no record that any further investigation has been conducted.
Lead Technician reported refusing to sign an Engineering Order due to compliance issues.