Safety Recommendation A-24-001

We note that, instead of revising the POHs, you have developed Service Letter (SL) 390 (issued May 3, 2024) and SL 391 (issued September 16, 2024), which include the recommended spin recovery techniques for the Twin Commander Aircraft 690, 690A, and 690B models.

We believe the information you have included in the SLs is positive; however, because SLs may only be distributed to aircraft owners/operators and maintenance personnel, we are concerned that this information may not reach all pilots of these aircraft. Therefore, we encourage you to also include this information in the applicable POHs.

Pending your plans to ensure that this critical safety information is distributed to pilots, Safety Recommendation A-24-1 is classified OPEN-- ACCEPTABLE RESPONSE. If you have any questions about this safety recommendation, please contact Mr. Nathaniel Hoyt.

Please update us at ExecutiveSecretariat@ntsb.gov on your progress toward addressing Safety Recommendation A-24-1, and do not submit both an electronic and a hard copy of the same response.

-From Gareth Hall, CEO, Managing Director and President, Ontic Engineering and Manufacturing, Inc.: We have reviewed the recommendations in your January 22, 2024, letter regarding the inclusion of a spin recovery procedure in the Twin Commander Aircraft Pilot Operating Handbook and appreciate the NTSB’s recommendations.

After careful consideration (including review of airworthiness regulations), and to expedite release of the spin recovery procedure to owners, operators, and other interested persons and entities, we have decided to issue a Service Letter in lieu of revising the Pilot Operating Handbook. The Service Letter will be released no later than Friday May 3, 2024, detailing Spin Recovery Techniques for the 690, the 690A, and the 690B Twin Commander models.

Twin Commander agrees with the NTSB’s assessment that airworthiness regulations for normal-operating aircraft do not require spin recovery techniques to be included within the Pilot Operating Handbook.

If I can be of any further assistance, please reach out at your convenience.

The NTSB is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant events in the other modes of transportation—railroad, transit, highway, marine, pipeline, and commercial space. We determine the probable cause of the accidents and events we investigate, and issue safety recommendations aimed at preventing future occurrences. In addition, we conduct transportation safety research studies and offer information and other assistance to family members and survivors for any accident or event investigated by the agency.

We also serve as the appellate authority for enforcement actions involving aviation and mariner certificates issued by the Federal Aviation Administration (FAA) and US Coast Guard, and we adjudicate appeals of civil penalty actions taken by the FAA.

The attached letter from the NTSB Chair provides information about the NTSB’s December 28, 2023, report Publish Spin Recovery Techniques for Twin Commander Aircraft, NTSB/AIR-23-02. The details of this accident investigation and the resulting safety recommendation may be found in the attached report, which can also be accessed at http://www.ntsb.gov. For more information about NTSB and our recommendation process, please see the attached one-page summary.

The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendation by number (for example, A-24-1). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.

All communications regarding safety recommendations will be stored by the NTSB and viewable by the public. Please do not send privileged or confidential communications in response to this recommendation. Responses marked as confidential or privileged (or similar designations) will be considered nonresponsive. If you have concerns about this protocol, please contact us at ExecutiveSecretariat@ntsb.gov.