The FAA has released a final ruling to create a SIC Professional Development Program that operators may choose to participate in via Op Spec, allowing SICs to log all the flight time towards new certificates and ratings.
Beginning on page 30240, here's some excerpts
"The FAA proposed to revise § 61.159(c)(1) to contain the requirements for logging SIC pilot time in an operation conducted under part 135 that does not require an SIC by type certification of the aircraft or the regulations under which the flight is being conducted."
"...the FAA is revising proposed § 61.159(c) to allow pilots to credit time logged under a SIC PDP not only for total time as a pilot, but also toward the specific flight time requirements for ATP certification set forth in § 61.159(a)(1) through (4) (e.g., cross-country flight time, night flight time, flight time in class of airplane, and instrument flight time). "
" the FAA maintains in the final rule that a SIC logging flight time under § 61.159(c) is not permitted to log this flight time as PIC time even when he or she is the sole manipulator of the controls"
" the FAA has decided to also allow SIC flight time to be logged during part 91 flight operations (e.g., re-positioning flights) conducted for the certificate holder when the operation is conducted in accordance with the certificate holder’s operations specification for the SIC PDP."
"Therefore, in the final rule, the amendments to §§ 61.39, 61.51(e) and (f), 61.159(a) and (c), 61.161, and 135.99(c) will be effective 150 days after publication of this final rule"
Originally the SIC PDP would apply only to multi engine aircraft, but thanks to several contributors (including my company, Tradewind Aviation!) single engine turbine aircraft are included.
Link to the Ruling