TURBO PRODUCTS INC.
Pond Meadow Road
P. O. Box 457
Ivoryton, CT 06442
INSPECTION REQUIREMENTS FOR;
PT6A TURBINE VANE RING
MANUFACTURED BY TURBO PRODUCTS INC.
P/N T032651
The P/N T032651 Turbo Products PT6A turbine vane ring is a replacement for PWC P/N 3032651, et al. The Federal Aviation Administration (FAA) has granted Production Approval (formerly FAA Parts Manufacturer Approval (PMA)) to Turbo Products because this vane ring is physically and functionally interchangeable with the PWC turbine vane ring it replaces. Since this Turbo Products turbine vane ring is physically and functionally interchangeable with the PWC turbine vane ring it replaces; this turbine vane ring is to be installed, operated, and removed in accordance with existing PWC PT6A maintenance manuals. HOWEVER, since this turbine vane ring incorporates design improvements which the PWC turbine vane ring does not offer; different inspection and repair procedures are appropriate. This Inspection Requirements document has been prepared to make this inspection information available to users of Turbo Products turbine vane rings. This Inspection Requirements document may be shared with any airworthiness regulatory authority approved maintenance facility, if they are working on PT6A engines with Turbo Products turbine vane rings.
Note: Acceptance criteria herein are based on structural integrity considerations and apply only if engine performance was satisfactory before H.S.I. Replace the vane ring with a new or an overhauled one of the same classification if its condition appears to be the cause for loss of performance. If inspection and / or repair / overhaul is appropriate, send the vane ring to the overhaul facility listed in this procedure for overhaul inspection and possible overhaul.
1. Removal / Installation:
See PWC PT6A Maintenance Manual for removal / installation instructions. Maintenance Manual locations are listed at the end of this procedure.
2. Maintenance Inspection:
A. Compressor Turbine Vane Ring, P/N T032651.
Inspect vane ring (See figure on page 5)
Vane Ring, Page 1, Mar.31, 1999, Intended for general distribution.
LOSS OF COATING
Vanes, Outer Ring, Inner Ring - Maximum Serviceable - Not critical without erosion. Note: If there is more than an isolated loss of coating, vane ring overhaul is economically prudent. Loss of coating without erosion of parent metal is repairable at overhaul. However, anything which exceeds minor / localized erosion is frequently not repairable at overhaul.
CRACKS
Vane trailing edges - Maximum Serviceable - Open cracks up to 0.500 inch long are acceptable on any number of vanes provided their progression will not result in loss of vane material.
Outer Ring - CAUTION: OUTER RING CRACKS ARE ACCEPTABLE ONLY IF SLOT-TO-LUG CLEARANCE CAN BE OBTAINED AT ASSEMBLY (REFERENCE PWC MAINTENANCE MANUAL, INSTALLATION SECTION)- Maximum Serviceable - Three cracks across the length of the outer ring are acceptable. Outer ring cracks that extend into vanes are acceptable. Multiple hairline cracks in, but not across, the ring are acceptable.
Inner Ring - Maximum Serviceable - Up to ten through cracks are acceptable provided they are not convergent and / or do not display signs of air leakage.
Note: If there are any open cracks, parent metal erosion or burning, vane ring overhaul is economically prudent. Open cracks can lead to erosion and burning which eventually causes the complete set of compressor turbine blades to be scrapped (see below).
EROSION AND BURNING
Vanes - Maximum Serviceable - 0.005 inch deep on any airfoil surface on any number of vanes.
When compressor turbine vane ring inspection reveals that vane trailing edge burning has resulted in loss of airfoil area of 0.125 sq. in. (i.e. average length times average width equals 0.125 sq. in.) or more, on any one vane, and burned area can be seen from leading edge of vane ring when viewed parallel to engine longitudinal axis, the entire set of compressor turbine blades must be scrapped. Comment: vane ring airfoil erosion and burning this severe is usually not repairable at overhaul.
Outer Ring, Inner Ring - Maximum Serviceable -Any amount.
CONTOUR
Maximum Serviceable -Vane airfoil contour distortion or surface irregularities may degrade engine performance; a cracked outer ring may incur geometric location errors in the slots which effect small exit duct fit and therefore shroud segment concentricity. These effects must be considered in determining the serviceability of the vane ring. Caution: Outer ring cracks are acceptable only if slot-to-lug clearance can be obtained at assembly.
Vane Ring, Page 2, Mar.31, 1999, Intended for general distribution.
DISTRESSED VANES
If distressed vanes are encountered, check fuel nozzles for proper functioning. A vane ring with vane leading edges damaged by malfunctioning fuel nozzles may be retained in service provided that:
1. No more than two vanes are damaged.
2. Damaged vanes are not adjacent to each other.
3. There is no engine performance deterioration attributable to the damage.
4. The loss of vane airfoil area at leading edge is less than 0.100 square inch with a maximum cordwise depth of 0.100 inch measured from leading edge.
5. The remaining part of the damaged vane retains its original airfoil shape.
6. If desired, the vane ring may be re-indexed to a new position 90 degrees from original position on assembly and remarked. Compressor turbine blade tip clearance must be rechecked following re-indexing.
GENERAL NOTES
1. Replace vane rings exhibiting defects in excess of Maximum Serviceable limits.
2. Acceptance criteria herein are based on structural integrity considerations and apply only if engine performance was satisfactory before H.S.I. Replace the vane ring with a new or an overhauled one of the same classification if its condition appears to be the cause for loss of performance.
3. Classification: When compressor turbine vane ring is to be replaced, a vane ring of the same class, or within +- 0.10 or less variation of the class from the last test cell performance run, is recommended for installation.
Note: If vane ring class is unknown, refer to the last test cell performance run (log book), or contact the previous facilities which performed maintenance or repair on the hot section.
B. CT Vane Ring Classification
Note: The following information is provided only as a guide, with the understanding that the speed (Ng) and temperature (ITT) response will be influenced by the ambient temperature and / or compressor condition. This information is based on overhaul experience. Installation losses and the condition of related assembly components are not accounted for.
1. An increase in CT vane ring class will reduce the gas generator speed (Ng).
2. An increase in PT vane ring class will increase the gas generator speed (Ng).
3. The reverse is true in both cases.
4. The ITT (T5) goes up when the Ng goes down, and vice versa.
5. On average, a 100 rpm increase in Ng will reduce T5 by 5 degrees R.
6. On average, a 0.10 class change will change Ng 80 - 100 rpm.
Vane Ring, Page 3 Mar. 31, 1999, Intended for general distribution.
C. Send vane rings to the following overhaul facility for complete overhaul inspection and refurbishment (i.e. inspection, repair, and re-coating). Note, have the vane ring disassembled from the small exit duct / vane ring / shroud housing assembly prior to shipment for overhaul inspection and refurbishment.
Dean Machine Products Inc.
102 Colonial Road
Manchester, CT 06040
1-800-966-5265 voice
1-860-649-5265 voice
1-860-647-7342 FAX
D. References: This Inspection Requirements document is intended to supplement Pratt and Whitney Canada maintenance manuals and manual locations as follows:
PT6A-21, 27, 28 Maintenance Manual, P/N 3013242
Section 72-52-41, pages 201 through 221.
PT6A-11, 11AG, 15AG, 110, 112, 121 Maintenance Manual, P/N 3030442
Section 72-50-11, pages 201 through 220, including 202A, 208A, 208B, 208C.
PT6A-25, 25A Maintenance Manual, P/N 3027542
Section 72-52-01, pages 201 through 226.
This Inspection Requirements document is Federal Aviation Administration, Designated Engineering Representative (FAA DER) approved.
Vane Ring, Page 4, Mar. 31, 1999, Intended for general distribution.