How to deal with and approach structural repairs on C-Check to release aircraft on time?

One of significant items that affects aircraft RTS (Release To Service) date is structural repairs. I mean the repairs that are OUT OF SRM. Such repairs invite risk of uncertainty in terms of required resources and time that potentially can lead to aircraft delay.?

The uncertainty appears in the following:

1. Time & MHs to be spend?

2. Materials required?

3. Materials delivery time

4. Special processes involved (heat treatment, anodizing, cadmium plating, NDT. etc.).

Airlines are not able to avoid these repairs except utilizing fresh or new aircrafts. However, it is possible to minimize or avoid the delay doing everything consequently and professionally.

Definitely, both MRO and Airline have the same goal - accomplish a C-check within agreed timeframe. MRO has already reserved slot for the next customer. Airline requires aircraft for commercial flights. More time aircraft stays on the ground less revenue it brings and more expensive becomes in terms of lease payments.

It is important to keep concentration on the goal and strive towards its achievement. For that, all actions and communication for the repair evaluation and embodiment should be fast.

How to be FAST?

OUT OF SRM repairs require OEM or Part 21J DO support for repair disposition development.

Some Airlines prefer to communicate to OEM/Part 21 themselves, let’s say to their CAMO. Just imaging that MRO production engineer sends a query to MRO Engineering, MRO Engineering send it to airline CAMO, airline CAMO to OEM/Part 21J DO. Do you see how long this communication channel? This way is already winless and could lead to delay.

Point No 1

The MRO Engineering team can keep it going, just let Airline CAMO monitor this process. Therefore, the best way to be FAST is to leave this problem with MRO.

Yes, MRO will charge Airline for the their engineering hours but just think how much?does this cost comparing to one flight hour or flight week.

Point No 2

Airlines should provide MRO with full access to all available DWGs that are applicable to their aircraft. I mean that it should be direct access to EOM web portal with all information but not “by request”. Some Airlines say: “We will provide DWGs and any information by request, just drop us an email”. What happens in this case? You drop them an email and wait...wait… because they are in another time zone or their Engineer busy with another stuff, etc.

Please keep in mind that all additional and unnecessary communication in terms of requests and emails between Airline CAMO and MRO Engineering leads to possible delay.

Some EOM allows delegating access from Airline to MRO or Airline can create a new access (log and pass) under their account and give it to the MRO for the period of C-Check. Use one of these options and let the repair to be accomplished on time.

Point No 3

Consistent report from production structure engineer on the found damage. Structure engineer is the first person who observes and defines that the damage is OUT OF SRM limits, so he is the one who should prepare a detailed report on that.

Pour report is a common issue and if this is a case than Engineering should provide guidelines for structure engineer to proceed and collect all required data about the damage for the repair development:

What could be included in this report?

(1) Part of airplane damaged and damage location.

·????????Identify the PN of the damaged part, Body stations, Buttock Line, nearest Stringers and provide the distance from known points on the structure to the center or edge of the damage.

(2) Damage description.

·????????Numerically identify each discrepancy and provide the type of damage (dent, crack, delamination, corrosion, short edge margin, etc.).

(3) Damage details (size).

·????????Identify the type and size (depth, length and width) of the damage.

·????????Any additional information relating to the adjacent structure of the damage needs to be added along with the corresponding dimension.

·????????Provide fasteners edge margins, hole sizes, hole spacing, etc.

·????????Provide distance to production cutout if damage is in close proximity.

·????????Report if the damage is near any existing repair, STC

(4) SRM limits. Provide reference to the SRM used (Chapter-Section-Subject-Pageblock-Procedure, Figure, repair procedure) confirming that the damage is OUT OF SRM ADL and no repair covering this damage is available.

(5) Damage removal?information.

·????????Blanding or Trimming, diminutions of area, thickness of material removed and maximum blend depth and ?it is helpful to provide a blend map

·????????DVI and NDT of affected and surrounding areas, open fasteners holes to confirm damage/ crack free condition. For example confirmed crack free by High Frequency Eddy Current (HFEC), Dye Pen. If it is composite material, confirm the extent of delamination by tap test, etc.

(6) Provide photographs, sketches, and/or drawings to help describe the damage or repair.

Provide photographs showing general area (zoomed out) for reference and additional photographs (zoomed in) to show enhanced details with orientation(s) labeled in each.

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IMPORTANT NOTE: It is generally preferable to remove the damage prior to submitting information to OEM / Part 21J DO for review EXCEPT for dents on metallic and composite structures, delamination or punctures to composite structure, and/or scribe to metallic or composite structure unless removal is already approved by SRM or service bulletin. Remove corrosion before submitting. In very complicated repairs, OEM / Part 21J DO can be contacted prior to removal of the damage.

This NOTE may slightly vary depending on the aircraft manufacturer but the basic approach is still the same. Please keep in mind that here I am talking about OUT OF SRM cases and the goal No 1 is NOT TO HURT / DAMAGE AIRCRAFT AND PERSONNEL.

If the reported damage is OUT OF SRM it means that the SRM practice becomes not applicable any more, other words you should stop and request OEM / Part 21 J?DO for support.?

On the other hand, we have to use our previous experience, knowledge, and best practice to open access, remove the damage, collect all required data, evaluate and initiate communication with OEM or Part 21 J DO.

To take a short conclusion, we have to keep balance between:

·????????Guidelines in the approved maintenance documentation,

·????????Safety operation and action,

·????????Possible risk we take,

·????????Aviation regulations rules,

·????????Our awareness what we do and which consequences it can lead to.

Point No 4

Repair Proposal. The BEST practice when Engineering Engineer, submitting a request to OEM/Part 21J DO, provides:

·????????Proposed repair using the SRM as guideline or Communication System Message number if referencing previously submitted repairs,

·????????Complete detail with sketches,

·????????List of deviations if applicable,

·????????Specify the proposed repair material to be used,

Actually, developing a repair proposal, a good one, takes significant amount of time.

·????????If your goal is to be FAST you may submit the request without proposal, in any case OEM/ Part 21 J DO charges for such developing. They definitely will do their calculation, analyzes, and create a solution. The question is "why to spend time proposing something?"

·????????If you would like to appear SMART and PROFESSIONAL, then YES prepare your own detailed comprehensive proposal. One well done proposal can take up to 3,4,5 etc. hours depending on the difficulty of the case and other factors.

·????????If you would like to appear SMART, PROFESSIONAL and FAST, then take a quick review of the similar cases, Communication System Messages with OEM etc and propose your repair plan base on that.

As you see, there are different variations of approach to repair proposal are exist. Selecting the way to go you have to take into consideration your goal, available resources & time, workload you have, Customer preferences and find the best options that suits these requirements. However, once again, focus on the main goal of the whole C-Check project is to release aircraft on time.

I have listed 4 points to deal with and approach structural repairs on C-Check to release aircraft on time.

1.???Leave all communication with OEM / Part 21 J DO to MRO,

2.???Provide full access to DWGs,

3.???Prepare detailed report on the damage,

4.???Propose repair plan.

This is my experience and my own view. I do not say that it is correct or not. You should select your own way considering surrounding factors.

Please share your experience, comment this article and please share it with you friends if find it deserving other attention.

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