A small jet pilot reported ramp personnel did not remove the towing adapter when preparing for departure which resulted in the nose gear stuck in a partially retracted position during gear retraction. The reporter was able to land safely with almost no damage.

Narrative

In preparation for departure the line service tech asked if I would like to sit in the aircraft as they pulled the aircraft out of the hangar to the ramp. By staying in the aircraft and not assisting with the 'spotting' of the towing I was not able available to double check and verify the readiness of the aircraft. The line service tech therefore forgot to remove the towing adapter. In our normal day to day operations we very seldom if ever require a towing adapter. I therefore departed with the adapter installed in the nose strut. After takeoff and during gear retraction I heard a loud bang; that was the exact time I realized he had forgot to remove the adapter. I performed the various Quick Reference procedures with no positive results. I finally realized that the nose gear was locked in its 3/4 retracted position and decided the only option left was to land and hope that the nose gear was extended sufficiently and secured enough to support the nose weight of the aircraft. After landing I held maximum back pressure on the elevator until a full stop. The nose tire made contact with the runway at approximately 35 knots with very little runway drift. After rolling to a stop I shut both engines; turned off the electrical power and vacated immediately. The local [responders] and fire fighters were ready for action. It was then that I documented that we had sustained almost no damage and proceeded to dolly the nosewheel and remove the aircraft from the now closed runway; but not after contacting the FAA personnel; along with the NTSB for permission. We also contacted them when the aircraft had been removed and allowed the runway to be re-activated from my early call to ZZZ Center to activate a runway closure immediately.