Keep STC hard copies or are digital versions sufficient?

[Winger67]

Going through 50 years of doc on my 1973 Cardinal RG and while I know anything unique to the plane serial number like 337s are definitely keepers, are digital versions of STCs good enough for documentation for the FAA and new owners? As far as I can tell, the STCs are standard and not uniquely tied to the aircraft of signed by the A&P or IA.

 

[Bell206]

As far as I can tell, the STCs are standard and not uniquely tied to the aircraft of signed by the A&P or IA.

FWIW: While 91.417 doesn't call out STCs by name they can be tied directly to a 337 by aircraft serial number. However, not all STCs are considered major alterations so there are some that are merely reference. Also per 91.403(d) most STCs need a permission letter which should be kept with the STC data package. Regardless, electronic versions are up to the owner. I'm old school and prefer certain docs in hardcopy like STCs and their data packages.

 

[NordicDave]

I have both paper and electronic. The log books from my plane are worth $10's K dollars and back-ups are essential. Paper just seems to endure.

A few techie guys here will have it on computer, back-up in a cloud server, and a DVD in a safe. Keeping everything sync'd gets to be a pain. Subscribing to a service makes a person beholden to that provider.

EDIT: @bnt83 's list below is excellent. I have the same docs in a 3-ring binder individually plastic sleeved in sections and some segregated in separate binders.

 

[bnt83]

Keep everything, paper and electronic.

Letters of Authorizations
STC Certificates
Master Data/Document Lists
Structural & Electrical Drawings
Installation Manuals
Instructions for Continued Airworthiness
Airplane Flight Manual Supplements
Electrical Load Analysis/Supplements
Operating Manual Supplements
Configuration Documents
Parts trace paperwork such as FAA form 8130-3, shipping/pick tickets for equipment other than basic items like tires, brake linings, nuts and bolts.
Invoices for Warranty Claims
Pictures of every page of all logbooks
Equipment Lists and Revisions
All Weight and Balance records
Any burn certifications for interior
AD Compliance Summary

I'm sure I am forgetting something.

 

[Jorge Gonzalez]

The STC cover sheet itself is no issue. You can download it from the FAA website as long as you know the number.
Its the Letter of Authorization (Rights to Use) that you need to make sure you save. This is what gives you the authorization to use the STC. This does not matter how you keep it. Digital in a folder in dropbox or cloud or whatever or a hard copy. You can always print it when you need it.