--- title: "EASA issues Airworthiness Directive for SportStar RTC, Viper SD-4, Breezer B600, PS-28 Cruiser in EU; compels inspection of propeller gearboxes." sdDatePublished: "2026-09-02T08:08:00Z" source: "https://ad.easa.europa.eu/blob/EASA_AD_2026_0170.pdf/AD_2026-0170_1" topics: - name: "air transport" identifier: "medtop:20000338" - name: "transportation accident and incident" identifier: "medtop:20000143" - name: "safety of citizens" identifier: "medtop:20000619" - name: "regulatory authority" identifier: "medtop:20001173" locations: - "Zlín" - "Germany" --- EASA issues Airworthiness Directive for SportStar RTC, Viper SD-4, Breezer B600, PS-28 Cruiser in EU; compels inspection of propeller gearboxes. TE - Airworthiness Directive EASA AD No.: 2026-0170 TE.CAP.00110-012 © European Union Aviation Safety Agency. All rights reserved. ISO9001 Certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet. An agency of the European Union Page 1 of 5 Airworthiness Directive AD No.: 2026-0170 Issued: 01 September 2026 Note: This Airworthiness Directive (AD) is issued by EASA, acting in accordance with Regulation (EU) 2018/1139 on behalf of the European Union, its Member States and of the European third countries that participate in the activities of EASA under Article 129 of that Regulation. This AD is issued in accordance with Regulation (EU) 748/2012, Part 21.A.3B. In accordance with Regulation (EU) 1321/2014 Annex I Part M.A.301, or Annex Vb Part ML.A.301, as applicable, the continuing airworthiness of an aircraft shall be ensured by accomplishing any applicable ADs. Consequently, no person may operate an aircraft to which an AD applies, except in accordance with the requirements of that AD, unless otherwise specified by the Agency [Regulation (EU) 1321/2014 Annex I Part M.A.303, or Annex Vb Part ML.A.303, as applicable] or agreed with the Authority of the State of Registry [Regulation (EU) 2018/1139, Article 71 exemption]. Design Approval Holder’s Names: EVEKTOR, spol. s.r.o. TOMARK, s.r.o. Strojnícka 5 080 01 Prešov Breezer Aircraft GmbH & Co. KG Czech Aircraft Group s.r.o. Type/Model designation(s): SportStar RTC aeroplanes; Viper SD-4 aeroplanes; Breezer B600 aeroplanes; PS-28 Cruiser SportCruiser / PiperSport aeroplanes. Effective Date: 08 September 2026 TCDS Number(s): EASA.A.592, EASA.A.606, EASA.A.598 and EASA.A.546 Foreign AD: Not applicable Supersedure: None ATA 72 – Engine – Propeller Gearbox – Inspection Manufacturers: Evektor-Aerotechnik a.s.; Tomark s.r.o.; Breezer Aircraft GmbH & Co. KG.; Czech Sport Aircraft Group a.s., formerly Czech Aircraft Group s.r.o.; Applicability: • Evektor SportStar RTC aeroplanes, all manufacturer serial numbers (MSN) equipped with a BRP- Rotax 912 ULS2 engine; and • Tomark Viper SD-4 RTC aeroplanes, all serial numbers (s/n) equipped with a BRP-Rotax 912 ULS2 engine; • Breezer B600 aeroplanes, all s/n equipped with a BRP-Rotax 912 ULS2 engine; • Czech Aircraft Group PS-28 Cruiser aeroplanes, all s/n equipped with a BRP-Rotax 912 ULS2 engine. Definitions: For the purpose of this AD, the following definitions apply: EASA AD No.: 2026-0170 TE.CAP.00110-012 © European Union Aviation Safety Agency. All rights reserved. ISO9001 Certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet. An agency of the European Union Page 2 of 5 The ASB: BRP-Rotax Alert Service Bulletin (ASB) ASB_2026-001 and/or ASB_A-2026-001. The SB: Evektor Mandatory Bulletin (MB) No. RTC-083a SR, Tomark ASB ASB_SD4-04-20, Czech Aircraft Group ASB ASB-CR-121 or Breezer Service Bulletin SB26-001, as applicable depending on aeroplane type, all referring for details to the ASB, as defined in this AD. Affected gearbox(es): Propeller gearbox(es) having a Part Number (P/N) as listed in Chapter 1.1 (Applicability) of the ASB and having a s/n as listed in Chapter 4.1 or 4.2 (Appendices) of the ASB, except those propeller gearboxes which are manufactured or overhauled after the effective date of this AD and those gearboxes which have passed (no discrepancy found, or applicable corrective actions accomplished) the inspection in accordance with the instructions of the ASB. Serviceable gearbox: Any propeller gearbox, eligible for installation in accordance with BRP-Rotax instructions, which is not an affected gearbox, as defined in this AD. Note 1: Chapter 4.1 (Appendix) of the ASB provides, for information only, the s/n of the engines on which the listed affected gearboxes are latest known to be installed. Affected engine(s): BPR-Rotax 912 UL, ULS, iS2Sport and 914 UL (Series) engines having installed an affected gearbox. Groups: Group 1 aeroplanes are those equipped with an affected engine that, on the effective date of this AD, has an affected gearbox installed that has accumulated less than 25 hours of operation since first installation on an engine. Group 2 aeroplanes are those equipped with an affected engine that, on the effective date of this AD, has an affected gearbox installed that has accumulated 25 or more hours of operation since first installation on an engine. Group 3 aeroplanes are those which are not Group 1 and are not Group 2. Reason: An occurrence was reported, where on a recently manufactured engine it was found that in the propeller gearbox the oil spray nozzle and the M7 x 16 hexagon screws, securing the propeller shaft bearing in the propeller gearbox were missing. Further investigation determined that those parts had not been installed during production, and that the missing screws may allow axial displacement of the propeller shaft bearing during operation, which could cause the propeller shaft and its front bearing to slightly move into of the gearbox housing. This condition, if not detected and corrected, could lead to in-flight loss of engine oil and/or an uncommanded engine shutdown, possibly resulting in loss of control of the aeroplane, although it is unlikely that the propeller shaft will be pulled out of the gearbox in flight. To address this potential unsafe condition, BRP-Rotax published the ASB, as defined in this AD, to provide instructions for inspection of the propeller gearbox and for corrective actions. Consequently, EASA published Emergency AD 2026-0121-E to require a one-time inspection of all the propeller gearboxes installed on certain certified Rotax 912, 912i and 914 (series) engines and, depending on findings, accomplishment of applicable corrective action(s). EASA AD No.: 2026-0170 TE.CAP.00110-012 © European Union Aviation Safety Agency. All rights reserved. ISO9001 Certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet. An agency of the European Union Page 3 of 5 Since that AD was issued, it was realised that some of the affected propeller gearboxes may also be installed on BRP-Rotax 912 UL, ULS, iS2Sport or 914 UL (series) engines, which do not have an EASA engine type certificate (TC), but which are certified as part of the aeroplane. Consequently, the same unsafe condition may exist or develop on general aviation aeroplanes which are equipped with such an affected engine. To address this potential unsafe condition, the TC Holders of these affected aeroplanes published the SB, as applicable, to provide instructions for inspection of the affected propeller gearboxes and applicable corrective action(s). For the reason described above, this AD requires a one-time inspection of the propeller gearbox and, depending on findings, accomplishment of applicable corrective action(s). Required Action(s) and Compliance Time(s): Required as indicated by this AD, unless the action(s) required by this AD have been already accomplished: Inspection(s): (1) Within the compliance time specified in Table 1 of this AD, inspect the propeller gearbox for presence of the oil spray nozzle assembly and the M7 x 16 hexagon screws in accordance with the instructions of the SB. Table 1 – Compliance Times Threshold for Inspection Group 1 aeroplanes Before next flight Group 2 aeroplanes Within 5 flight hours, but without exceeding 12 months, after the effective date of this AD Corrective Action(s): (2) If, during the inspection as required by paragraph (1) of this AD, it is found that the M7 x 16 hexagon screws and/or oil nozzle assembly are missing in the propeller gearbox, before next flight, replace the gearbox with a serviceable gearbox, as defined in this AD, in accordance with the instructions of the SB. (3) Replacement on an aeroplane of the propeller gearbox with a serviceable gearbox is an acceptable method to comply with the requirements of paragraph (1) of this AD for that aeroplane. This can be accomplished in accordance with the applicable Aircraft Maintenance Manual. (4) Replacement of the engine of an aeroplane with an engine having a serviceable gearbox installed is an acceptable method to comply with the requirements of paragraph (1) of this AD for that aeroplane. This can be accomplished in accordance with the applicable Aircraft Maintenance Manual. EASA AD No.: 2026-0170 TE.CAP.00110-012 © European Union Aviation Safety Agency. All rights reserved. ISO9001 Certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet. An agency of the European Union Page 4 of 5 Parts Installation: (5) For Group 1, Group 2 and Group 3 aeroplanes: From the effective date of this AD, it is allowed to install on any aeroplane a propeller gearbox, provided that it is a serviceable gearbox. (6) For Group 1, Group 2 and Group 3 aeroplanes: From the effective date of this AD, it is allowed to install on any aeroplane an affected engine, provided that it is equipped with a serviceable gearbox. Ref. Publications: Evektor MB No. RTC-083a SR original issue dated 17 July 2026. Tomark ASB ASB_SD4-04-2026 original issue dated 30 June 2026. Breezer Aircraft SB26-001 original issue dated 19 August 2016. Czech Aircraft Group ASB ASB-CR-121 original issue dated 29 June 2026. BRP-Rotax ASB ASB_2026-001 original issue dated 22 June 2026 and/or ASB_A-2026-001 original issue dated 22 June 2026. The use of later approved revisions of the above-mentioned documents is acceptable for compliance with the requirements of this AD. Remarks: 1. If requested and appropriately substantiated, EASA can approve Alternative Methods of Compliance for this AD. 2. Based on the required actions and the compliance time, EASA have decided to issue a Final AD with Request for Comments, postponing the public consultation process until after publication. All interested persons may send their comments, referencing the AD Number, to the E-mail address specified in below Remark 3, prior to 29 September 2026. Only if any comment is received during the consultation period, a Comment Response Document will be published in the EASA Safety Publications Tool, in a compressed (‘zipped’) file, attached to the record for this AD. 3. Enquiries regarding this AD should be referred to the EASA Safety Information Section, Certification Directorate. E-mail: ADs@easa.europa.eu. 4. Information about any failures, malfunctions, defects or other occurrences, which may be similar to the unsafe condition addressed by this AD, and which may occur, or have occurred on a product, part or appliance not affected by this AD, can be reported to the EU aviation safety reporting system. This may include reporting on the same or similar components, other than those covered by the design to which this AD applies, if the same unsafe condition can exist or may develop on an aircraft with those components installed. Such components may be installed under an FAA Parts Manufacturer Approval (PMA), Supplemental Type Certificate (STC) or other modification. EASA AD No.: 2026-0170 TE.CAP.00110-012 © European Union Aviation Safety Agency. All rights reserved. ISO9001 Certified. Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet. An agency of the European Union Page 5 of 5 5. For any question concerning the technical content of the requirements in this AD, please contact, as applicable depending on the aeroplane type: Evektor, spol. s r.o., Letecká 1008, 686 04 Kunovice, Czech Republic, Tel