Engine shop visit
Boeing 737NG engine shop-visit records review
This review examines the shop-visit package behind a Boeing 737NG's CFM56 engines so the incoming side can confirm what each visit actually did to the engine's standing. It is run by or for the party valuing or taking on the aircraft, where shop-visit history drives engine value and LLP position. It reconciles the workscope, module build sheets, test-cell results, and release evidence against the engine status the records claim. You receive a shop-visit reconciliation per engine, a list of build or trace points that do not tie out, and the release evidence assembled for each visit.
When this review is needed
- A 737NG is being valued and its CFM56 shop-visit history sets a large part of the engine value.
- An engine came off a shop visit and the build sheets need to reconcile to the status it left with.
- A workscope was quoted as one level but the package suggests a different scope was performed.
- Module LLP standing has to be confirmed against the build records before an engine changes hands.
The problem
A shop-visit report can state a status the build records underneath it do not fully support. On a 737NG, a CFM56 shop visit produces a thick package, workscope, module build sheets, test-cell data, and release certificates, and the engine's value rests on what those documents actually say rather than the summary at the front. When the build sheets, the LLP standing, and the release do not tie together, the engine is worth less than its report implies, and the gap only shows when someone reconciles the package line by line.
What gets reviewed
- The workscope for each shop visit against what the build records show was performed
- Module build sheets reconciled to the engine's post-visit status
- Test-cell data supporting the engine's serviceability at release
- Release certificates for the engine and its modules after each visit
- Module LLP standing confirmed against the build records
- Build or trace points across the visit that do not tie out
Scope this review
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Send a representative, redacted record set and we will scope the review.
What gets validated
- The recorded workscope matches the module build sheets for the visit
- Post-visit engine status reconciles with the build records rather than the summary alone
- Test-cell results support the serviceability claimed at release
- Release certificates cover the engine and the modules the visit worked
- Module LLP standing after the visit agrees with the build sheets
Evidence normally required
- The engine shop-visit package for each visit on record
- Module build sheets and disk sheets from the visits
- Test-cell data and performance results at release
- Release certificates for the engine and its modules
- The engine status and LLP position claimed after each visit
Common discrepancies
- A recorded workscope the module build sheets do not fully support
- Post-visit status that does not reconcile with the build records behind it
- Module LLP standing on the summary that the build sheets contradict
- A visit missing the release certificate for a module it worked
What is at stake
An engine whose shop-visit package does not reconcile carries value that cannot be defended at a transfer, and a build point that does not tie out can put the LLP standing the price depends on into dispute. A workscope that was recorded but not fully supported by the build sheets leaves the buyer paying for a restoration the records do not prove, and reconstructing a shop visit after the fact is often impossible once the shop has moved on.
Move from findings to resolution
Move from findings to a documented resolution path.
How the work runs
Take the summary as claims
Treat the shop-visit report's stated status as assertions to be proven against the build records.
Reconcile the build
Tie the workscope, module build sheets, and test-cell data to the post-visit status.
Confirm module LLP standing
Check the module LLP position after the visit against the build sheets and release.
Report the untied points
List the build and trace points that do not reconcile, with the document behind each.
What the buyer receives
- A shop-visit reconciliation per engine tying the package to the claimed status
- A list of build or trace points that do not tie out, with the document behind each
- The release evidence assembled for each shop visit
Who uses the output
- Asset and remarketing teams pricing the engine value the shop-visit history supports
- Continuing-airworthiness teams confirming engine and module status before program entry
- Records teams assembling the shop-visit evidence a buyer or lessor will require
How the work fits into the transaction or program
The shop-visit review connects to the LLP trace and release reads on an incoming 737NG, since the module builds it examines are where engine LLP standing is set. Its reconciliation confirms the engine value that a large share of the aircraft's price rests on, and its list of untied build points drives recovery of missing build or release records while the shop that produced them is still reachable.
Aircraft-specific considerations
The CFM56 that powers the 737NG carries the highest-value documented history on the aircraft, and its shop-visit packages set both the engine value and the module LLP standing. An engine that has moved between airframes or through more than one shop is where a build point most often fails to tie out, because standing is reset at the module across visits that different shops performed.
Regulatory limits
The review reconciles the shop-visit records and confirms what they support. It does not certify the engine, set its serviceability or LLP life on an authority's behalf, or make an airworthiness determination on the engine or its modules.
What this review does not cover
- Physical inspection, test, or teardown of the engine or its modules
- Certifying the engine or issuing any release certificate
- Any airworthiness determination on the engine or its LLPs
Specific to this review
- The value of a 737NG engine sits in what its build sheets prove, not in the summary at the front of the shop-visit report.
- A build point that does not tie out can put the module LLP standing the price depends on into dispute, since standing is set at the module during the visit.
- A shop visit is nearly impossible to reconstruct after the shop moves on, so an untied build record found late has no clean path to recovery.
Sources
U.S. Government (eCFR). Maintenance recordkeeping content and approval-for-return-to-service requirements, including 43.9, 43.11, and Appendix B.
U.S. Government (eCFR). Records an owner or operator must keep, including total time in service, current status of life-limited parts, and AD compliance.
Federal Aviation Administration. Completion and use of FAA Form 8130-3, Authorized Release Certificate, for new and used parts.
European Union / EASA. Continuing airworthiness, maintenance records, CAMO responsibilities, and the airworthiness review process in the EASA system.
Frequently asked questions
Why reconcile the shop-visit package if a release certificate is present?
A release confirms the engine left serviceable, but the value rests on what the build sheets and module LLP standing actually show. On a 737NG, the CFM56 build records are where the money sits, and a workscope or module figure that does not tie out to the release is where the engine is worth less than its report implies.
Relevant glossary terms
Related pages
Where this fits
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