ZBW controller reported a citation descended early resulting in an airspace incursion.

Attributes
ACN	1528915
Time
Date	201803
Local Time Of Day	1201-1800
Place
Locale Reference	ZBW.ARTCC
State Reference	NH
Aircraft 1
Make Model Name	Citation Excel (C560XL)
Flight Phase	Descent
Route In Use	STAR ZELKA2
Flight Plan	IFR
Person 1
Function	Enroute
Qualification	Air Traffic Control Fully Certified
Events
Anomaly	Airspace Violation All Types Deviation - Altitude Crossing Restriction Not Met Deviation - Altitude Overshoot Deviation - Procedural Published Material / Policy Deviation - Procedural Clearance

Narrative:

While receiving a position relief briefing; aircraft X checked on; descending and nearly level at FL240; and the controller who I was relieving issued the clearance to descend via the ZELKA2 arrival. The procedure starts at eegul with no published altitude; but a published altitude of FL240 at the next fix; teria. Aircraft X was observed descending below FL240 in the vicinity of the eegul fix; which resulted in a violation of sector 22's airspace. This is my 3rd [report on] aircraft starting down too early on the zelka arrival. In each instance the pilots have said the computer started the aircraft down. For my three occurrences; three different type of aircraft have been involved. The procedure may need to [be] reevaluated and the start of the STAR or the published altitudes may need to be changed.

Original NASA ASRS Text

Title: ZBW controller reported a Citation descended early resulting in an airspace incursion.

Narrative: While receiving a position relief briefing; Aircraft X checked on; descending and nearly level at FL240; and the controller who I was relieving issued the clearance to descend via the ZELKA2 arrival. The procedure starts at EEGUL with no published altitude; but a published altitude of FL240 at the next fix; TERIA. Aircraft X was observed descending below FL240 in the vicinity of the EEGUL fix; which resulted in a violation of Sector 22's airspace. This is my 3rd [report on] aircraft starting down too early on the ZELKA arrival. In each instance the pilots have said the computer started the aircraft down. For my three occurrences; three different type of aircraft have been involved. The procedure may need to [be] reevaluated and the start of the STAR or the published altitudes may need to be changed.

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.