Brake lines rotted

[Skyhawk]

What you are referring to as a "bubble flare" is an "ISO flare" and it is different than a "double flare". ISO flares do require special flaring tools, as do double flares. ISO flares are commonly found with ABS brakes. The two flares are NOT interchangable. The patch job the OP suggests is OK, but not the best, or recommended, repair for the rotted line. A shop manual should be consulted for the recommended repair and replacement for the given make and model, etc.

[cdenk-h]

RickMN is correct, there is a difference between bubble and double. The common USA manufactured is double, while some foreign brands may be bubble. What I should have mentioned, was the difference between JIC, 37 degree flares and 45 degree flares. Aircraft = MS, Machine = JIC (Joint Industry Council)(Auto and other manufacturer's standard for their in plant machinery), and then there is the 45 degree. Each requires a different flare tool. All the doubles are 45 degree. Although the 37 degree will hold the pressure, fatigue could be an issue, and the fittings should be forged or machined from a billet, and not where the threaded end are brazed into a machined body.