Landing Clearnace on a Runway with Closed Portion?

My question is simple but proving the answer to be quite difficult. I am trying to find any regulation or publication that addresses the legallity of issuing a landing clearance to an aircraft with a portion of the runway being closed. So far all I can find on this particular issue is:

FAAO 7110.65 3-3-2 which does not specify only a portion, just a Closed Runway.

AIM 4-3-6. Use of Runways/Declared Distances
c. At some airports, the airport proprietor may declare that sections of a runway at one or both ends are not available for landing or takeoff. For these airports, the declared distance of runway length available for a particular operation is published in the Airport/Facility Directory. Declared distances (TORA, TODA, ASDA, and LDA) are defined in the Pilot/Controller Glossary. These distances are calculated by adding to the full length of paved runway any applicable clearway or stopway and subtracting from that sum the sections of the runway unsuitable for satisfying the required takeoff run, takeoff, accelerate/stop, or landing distance.

However this does not address whether or not you are authorized to clear an aircraft to land on the runway. I am looking for some input on this as to where it says you may clear an aircraft to land on that usable portion. I can not find anywhere that states the legallity of the clearance.

Any assistance would be greatly appreciated. If you know where I can find this please post the regulation.

i'll look at the books later, but for now look at displaced thresholds. is the front end or the back end closed?

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Usually the airport will just displace or relocate the threshold of the unaffected portion and report what section of it is closed by NOTAM. Unless the ENTIRE runway is closed, I don't see (from a pilot's standpoint) how this would be handled any differently than if the entire runway were available for use.

"Cleared to land runway xx, last xxxx feet closed."

yeah, I worked a runway closure for about 10 months... half the runway at a time with a huge steel barrier halfway down the runway. Its all in the displaced threshold.

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~controller since 99'

The way it was described to me is that there will be vehicles and ground equipment operating on the closed portion and it could be on the first, last or both portions with a small section in the middle only available for landing with a NOTAM issued. The only thing I can find reference this is that the appropriate markings must be in place and it has to be established in a facility directive. Since a NOTAM does not constitute a facility directive and it does not address vehicles/ground equipment, I say I would be reluctant to issue a landing CLEARANCE and the closed runway phraseology would be more correct. If anyone knows where I can find additional Regs it would be greatly appreciated.

if there is a displaced threshold and proper markings/lighting its not considered closed.

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~controller since 99'