Captain reported encountering issues with a ferry permit.

Attributes
ACN	1748820
Time
Date	202006
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Flight Phase	Parked
Flight Plan	IFR
Component
Aircraft Component	Elevator
Person 1
Function	Captain Pilot Flying
Qualification	Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine
Events
Anomaly	Aircraft Equipment Problem Less Severe Deviation - Procedural Published Material / Policy Deviation - Procedural Maintenance

Narrative:

Ferry aircraft with airframe vibration written up. Possible worn elevator hinges. Previous crew noted vibration occurred at 308 knots on climb through FL220 and 308 knots on climb through FL280.dispatch filed us above FL220 with no speed restriction. We contacted them and had them change our plan to cruise at FL190 no faster than 250 kt. The flight progressed without incident within these aforementioned parameters. Company was contacted [and] connected me to [a] ca (captain) who assisted me with my decision to accept this aircraft. I felt that I was in a realm outside the airworthiness of the aircraft. An ea (engineering authorization) suggested to me that the aircraft had been deemed not to be airworthy and data had been collected to confirm that it is safe to fly. My question was whether I was permitted to take such an aircraft as a non-test pilot. Apparently; I am.advise all line pilots that they may be placed in this scenario as the fleet apparently declines due to wear on elevator hinges.

Original NASA ASRS Text

Title: Captain reported encountering issues with a ferry permit.

Narrative: Ferry aircraft with airframe vibration written up. Possible worn elevator hinges. Previous crew noted vibration occurred at 308 knots on climb through FL220 and 308 knots on climb through FL280.Dispatch filed us above FL220 with no speed restriction. We contacted them and had them change our plan to cruise at FL190 no faster than 250 kt. The flight progressed without incident within these aforementioned parameters. Company was contacted [and] connected me to [a] CA (Captain) who assisted me with my decision to accept this aircraft. I felt that I was in a realm outside the airworthiness of the aircraft. An EA (Engineering Authorization) suggested to me that the aircraft had been deemed not to be airworthy and data had been collected to confirm that it is safe to fly. My question was whether I was permitted to take such an aircraft as a non-test pilot. Apparently; I am.Advise all line pilots that they may be placed in this scenario as the fleet apparently declines due to wear on elevator hinges.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.