Safety Recommendation A-16-054
Details
Synopsis: These recommendations are intended to prevent the incorrect installation of the reversing lever (beta arm) and related components in PT6A engines, which can cause the propeller to transition uncommanded to feather in flight. They are derived from investigations of accidents in which the beta arm or related components were found incorrectly positioned. As a result of these investigations, the NTSB is issuing one safety recommendation each to the FAA and Pratt & Whitney Canada. During the NTSB’s on-scene wreckage examination of a Beech 1900C airplane that collided with terrain following a loss of thrust in the left engine (a Pratt & Whitney Canada PT6A-65B) shortly after takeoff from Miami Executive Airport, Miami, Florida, the left engine's propeller beta arm was found incorrectly positioned over its guide pin rather than under it. (Figure 1 shows exemplar engines with correctly and incorrectly positioned beta arms.) If the beta arm is not secure under the guide pin, the unsecured linkage could release oil pressure in the beta valve and cause uncommanded travel of the propeller to the feather position. Although metallurgical analysis during the NTSB’s investigation determined that the incorrect beta arm position was a result of impact or postaccident forces and therefore not causal to the accident, the incorrect position of the component was identified as a finding in the investigation.
Recommendation: TO PRATT AND WHITNEY CANADA: As soon as practicable, complete the development and implementation of a redesigned guide pin assembly for PT6A engines to prevent the possibility of the reversing lever (beta arm) and guide pin being incorrectly installed.
Original recommendation transmittal letter: PDF
Overall Status: Open - Acceptable Response
Mode: Aviation
Location: Miami, FL, United States
Is Reiterated: No
Is Hazmat: No
Is NPRM: No
Accident #: ERA15FA129
Accident Reports:
Report #: ASR-16-07
Accident Date: 2/11/2015
Issue Date: 12/8/2016
Date Closed:
Addressee(s) and Addressee Status: Pratt & Whitney (Open - Acceptable Response)
Keyword(s):

Safety Recommendation History
From: NTSB
To: Pratt & Whitney
Date: 9/18/2020
Response: We continue to believe that your ongoing work with the original equipment manufacturer to design a new guide pin assembly that fits all installations is responsive to this recommendation. Pending completion of this effort and implementation of the redesigned guide pin assembly on aircraft equipped with PT6A engine models, Safety Recommendation A-16-54 remains classified OPEN--ACCEPTABLE RESPONSE. Please update us at ExecutiveSecretariat@ntsb.gov on your progress toward implementing this recommendation, and do not submit both an electronic and a hard copy of the same response.

From: Pratt & Whitney
To: NTSB
Date: 5/6/2020
Response: -From Jean-Francois Houle, Service Investigation Manager, Pratt and Whitney, Canada: P&WC recently completed the field trial fit of the new guide pin bracket onto the first target aircraft with the PT6A-114, PT6A-114A or the PT6A-140 engine models. The trial fit demonstrated the design intent of the new guide pin bracket, that when the propeller reversing lever (beta arm) – is incorrectly placed above the guide pin bracket during engine rigging, it would not allow the beta block to engage with the beta ring. Without engagement of the beta block in the beta ring, the engine would essentially stay in feather (as intended), until corrective action is done to the assembly and the propeller lever is correctly placed under the bracket pin. Subsequent to this trial fit, P&WC became aware that the PT6A-114/PT6A-114A/PT6A-140 on the Cessna Caravan (primary first installation target) had an additional sensor in the area (installed by the OEM – but not on the aircraft used for the trial fit) that is an option for operators to select at the aircraft level and that interfered with the new design guide pin bracket (could not fit the new guide pin bracket on the aircraft that had this particular aircraft sensor option). P&WC is currently working with the OEM on another design to avoid the guide pin bracket interfering with the aircraft sensor. The drawing for the new guide pin bracket will be released by end of May 2020. This will allow to create a 3D printed prototype for an OEM trial fit. P&WC is targeting incorporation into the first engine models in late 2020, and P&WC will continue to address other models, which will require trial fits on those installations. The end design intent is to have a configuration that fits all installations. In addition to the redesign of the guide pin bracket, P&WC continues to emphasize the correct installation of the reversing lever in all its continuing airworthiness documentation and at all training opportunities such as at operator conferences. Should you require any additional information at this point, please do not hesitate to contact me.

From: NTSB
To: Pratt & Whitney
Date: 3/4/2020
Response: You reported that you completed the field trial fit of the redesigned guide pin bracket on your initial target aircraft that are equipped with PT6A-114, PT6A-114A, or PT6A-140 engine models; however, on Cessna Caravan aircraft that are equipped with PT6A 114/PT6A 114A/PT6A-140 engine models, you discovered an additional sensor that was not on the aircraft used for the field trial fit and interferes with the redesigned guide pin bracket. We note that you are working with the original equipment manufacturer on another design that fits all installations. Pending completion of this effort and implementation of the redesigned guide pin assembly on aircraft equipped with PT6A engine models, Safety Recommendation A 16-54 remains classified OPEN--ACCEPTABLE RESPONSE. Please update us at ExecutiveSecretariat@ntsb.gov on your progress toward addressing this recommendation, and do not submit both an electronic and a hard copy of the same response.

From: Pratt & Whitney
To: NTSB
Date: 2/7/2020
Response: -From Jean-Francois Houle, Service Investigation Manager, Pratt and Whitney Canada: I would like to update you on the NTSB recommendation A-16-54: “As soon as practicable, complete the development and implementation of a redesigned guide pin assembly for PT6A engines to prevent the possibility of the reversing lever (beta arm) and guide pin being incorrectly installed.” P&WC recently completed the field trial fit of the new guide pin bracket onto the first target aircraft with the PT6A-114, PT6A-114A or the PT6A-140 engine models. The trial fit demonstrated the design intent of the new guide pin bracket, that when the propeller reversing lever (beta arm) – is incorrectly placed above the guide pin bracket during engine rigging, it would not allow the beta block to engage with the beta ring. Without engagement of the beta block in the beta ring, the engine would essentially stay in feather (as intended), until corrective action is done to the assembly and the propeller lever is correctly placed under the bracket pin.

From: NTSB
To: Pratt & Whitney
Date: 7/22/2019
Response: We note that you have completed the field trial fit of the redesigned guide pin bracket on your initial target aircraft that are equipped with PT6A-114, PT6A-114A, or PT6A-140 engine models, and you are currently seeking approval from the original equipment manufacturer and securing a production source for the parts. Pending implementation of the redesigned guide pin assembly on the initial target aircraft and aircraft equipped with other PT6A engine models, Safety Recommendation A-16-54 remains classified OPEN--ACCEPTABLE RESPONSE.

From: NTSB
To: Pratt & Whitney
Date: 4/15/2019
Response: We note that you have received the trial fit parts needed to begin your standard validation process, which includes installing a guide pin on the aircraft to ensure that there is no interference with aircraft equipment or propeller rigging activities. Pending introduction of the redesigned parts, Safety Recommendation A-16-54 remains classified OPEN--ACCEPTABLE RESPONSE.

From: NTSB
To: Pratt & Whitney
Date: 10/16/2018
Response: We note that you initiated the recommended redesign in February 2015, and you are currently in the final stages of evaluating the redesigned parts and plan to introduce them during 2019. Pending introduction of the redesigned parts, Safety Recommendation A-16-54 is classified OPEN--ACCEPTABLE RESPONSE.

From: NTSB
To: Pratt & Whitney
Date: 9/4/2018
Response: We are interested in knowing whether and how our recommendations are implemented, both to ensure that the traveling public is provided the highest level of safety and to identify creative solutions that might be shared with others. We normally expect actions to address our recommendations to be completed within 3 to 5 years, and we have yet to hear from you regarding your progress toward addressing this recommendation. We would appreciate receiving a response within 90 days indicating any actions you have taken or plan to take to implement the recommendation; until then, it retains its current classification of OPEN--AWAIT RESPONSE. Please update us at correspondence@ntsb.gov regarding your actions to address Safety Recommendation A 16 54, and do not submit both an electronic and a hard copy of the same response.

From: NTSB
To: Pratt & Whitney
Date: 12/8/2016
Response: On December 5, 2016, we adopted our report about preventing the incorrect installation of the reversing lever (beta arm) in Pratt & Whitney Canada PT6A engines.1 Additional information about the investigative background and analysis that led to the resulting recommendations may be found in the safety recommendation report, which can be accessed at our Aviation Information Resources webpage under NTSB report number ASR-16-007. As a result of this investigation, we issued one new recommendation to the Federal Aviation Administration and the following new recommendation to Pratt & Whitney Canada.