SP1520SO
Install Memphis Prop. counterweight thrust bearings in place of the Hamilton Standard counterweight thrust bearings. Held by Northwest Propeller Services INC., which holds 4 approved modifications in all. Last revised January 5, 1999. System: propeller.
What it applies to
- Kind of product
- Propeller
- Design holder
- Hamilton Standard Division; Hamilton Standard Division
- Models
- 12D40, 2D30
- Type certificates
- P-257, P-206
- The FAA's record
- On the FAA's site
What an approved modification is
A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.
Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 8, 2026.