TURBO PRODUCTS INC.
Pond Meadow Road
P. O. Box 457
Ivoryton, CT 06442
INSPECTION REQUIREMENTS FOR;
PT6A-6 SERIES AND -20 SERIES TURBINE VANES
MANUFACTURED BY TURBO PRODUCTS INC.
P/N T019551
The P/N T019551 Turbo Products PT6A turbine vanes are replacements for PWC P/N 3019551, et al. The Federal Aviation Administration (FAA) has granted Production Approval (formerly FAA Parts Manufacturer Approval (PMA)) to Turbo Products because these vanes are physically and functionally interchangeable with the PWC turbine vanes they replace. Since these Turbo Products turbine vanes are physically and functionally interchangeable with the PWC turbine vanes they replace; these turbine vanes are to be installed, operated, and removed in accordance with existing PWC PT6A maintenance manuals. HOWEVER, since these turbine vanes incorporate design improvements which the PWC turbine vanes do 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 vanes. 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 vanes.
Note: Acceptance criteria herein are based on structural integrity considerations and apply only if engine performance was satisfactory before H.S.I. Replace as many vanes as appropriate with new or overhauled ones of the same classification if their condition appears to be the cause for loss of performance. If inspection and / or repair / overhaul is appropriate, send the vanes to the overhaul facility listed in this procedure for overhaul inspection and possible overhaul.
1. Removal / Installation:
See PWC PT6A-6 Series and PT6A-20 Series Maintenance Manual P/N 3015442 for removal / installation instructions. Maintenance Manual locations are listed at the end of this procedure.
2. Maintenance Inspection:
A. Compressor Turbine Vane, P/N T019551.
Inspect vanes (See Figure 3-3-1A and Figure 3-3-1B)
CAUTION: IF ANY CT VANE HAS TRAILING EDGE BURN THROUGH AS SHOWN (See figure 3-3-1A), THE CT BLADES MUST BE DISCARDED, AND REPLACED WITH NEW OR OVERHAULED CT BLADES.
CT Vanes, Page 1, Mar. 31, 1999, Intended for general distribution.
Burned areas on vanes increase flow area which accelerates downstream component deterioration, decreases Ng and increases T5.
a. Cracks (See Figure 3-3-1B) are repairable. Keep the engine in service and monitor deterioration progression. Do an HSI before defects progress to such an extent that the CT vanes become un-repairable. If the CT vanes become un-repairable, this will increase the cost of the subsequent HSI. Inspect CT vane ring having the defects shown within 100 hours. Subsequent inspection must not exceed 400 hours.
b. If defects have progressed beyond repair limits shown, engine may remain in service, providing a ground power check (Refer to Aircraft Maintenance Manual) is done, and the airfoil trailing edge damage does not exceed limits shown (See Figure 3-3-1A). An HSI is recommended if the vane trailing edge defects are beyond the limits shown or down stream components are affected by the CT vane distress or engine performance is unacceptable.
Note: If there are any open cracks, parent metal erosion or burning, vane 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 previous page).
Component - Compressor Turbine Vanes --- Nature of Inspection - Cracks, coating loss, erosion of parent metal or impact damage.
COMPRESSOR TURBINE VANES
Inspection - Loss of coating --- Maximum Serviceable - 0.300 inch square on any airfoil surface --- Maximum Repairable - Not repairable at maintenance level --- Corrective Action - Return to overhaul facility for possible repair.
Note: If there is more than an isolated loss of coating, vane 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.
Inspection - Parent metal erosion --- Maximum Serviceable - 0.010 inch deep on any airfoil surface --- Maximum Repairable - Not repairable --- Corrective Action - Replace with new or overhauled vane of the same class.
Inspection - Trailing edge cracks --- Maximum Serviceable - Multiple hairline cracks not exceeding 0.100 inch long --- Maximum Repairable - Not repairable at maintenance level --- Corrective Action - Return to an overhaul facility for possible repair.
Inspection - Trailing edge cracks --- Maximum Serviceable - Not more than five cracks per vane, which exceed 0.185 inch long --- Maximum Repairable - Not repairable at maintenance level --- Corrective Action - Return to an overhaul facility for possible repair.
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Inspection - Trailing edge cracks --- Maximum Serviceable - Multiple hairline cracks not exceeding 0.100 inch long --- Maximum Repairable - Not repairable at maintenance level --- Corrective Action - Return to an overhaul facility for possible repair.
Inspection - Trailing edge cracks --- Maximum Serviceable - Not more than five cracks per vane, which exceed 0.185 inch long --- Maximum Repairable - Not repairable at maintenance level --- Corrective Action - Return to an overhaul facility for possible repair.
Inspection - Erosion and burning --- Maximum Serviceable - When a compressor turbine vane 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 or exceeds 0.125 sq. in.) or more, on any one vane and burnt area can be seen from the leading edge of the vane assembly when viewed parallel to the engine longitudinal axis, the entire set of compressor turbine blades must be scrapped. --- Maximum Repairable - Not repairable --- Corrective Action - Replace with new or overhauled vane of the same class. Comment: Vane airfoil erosion and burning this severe is usually not repairable at overhaul.
DISTRESSED VANES
If distressed vanes are encountered, check fuel nozzles for proper functioning.
NOTES: COMPRESSOR TURBINE VANES
1. Cracks longer than 0.125 in. must be separated by at least 0.100 in.
2. Cracks must not be open in excess of 0.020 in.
3. Classification, replace vane assembly with same class within +- 0.10 or less. If vane class unknown, refer to last test cell run matching figures in log book or contact the previous facilities which performed maintenance or repair on the hot section.
4. Replace vanes exhibiting defects in excess of maximum serviceable limits.
REPLACEMENT (VANES)
In the event of compressor turbine vanes requiring replacement, it is desirable to replace them with new or overhauled vanes of identical class. However, if original class of a defective vane cannot be identified, vanes of any class may be utilized provided that the total class average is equal to that determined at manufacture (first run engines) or last overhaul (overhauled engines).
NOTE: to arrive at a class average, add together class markings of all vanes and divide total figure by number of vanes.
B. CT Vane Assembly Average 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.
for.
1. An increase in CT vane assembly average class will reduce the gas generator speed (Ng).
2. An increase in PT vane ring or PT vane assembly average 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 assembly average class change will change Ng 80 - 100 rpm.
C. Send vanes to the following overhaul facility for complete overhaul inspection and refurbishment (i.e. inspection, repair, and re-coating). Note, have the (individual) vanes disassembled from the small exit duct / vanes / 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 manual and manual locations as follows:
PT6A-6 Series and PT6A-20 Series Maintenance Manual P/N 3015442
Pages 3-3-8A, 3-3-8B, 3-3-8C, 3-3-8D, 3-3-8E, 3-3-8F, 3-3-9, 3-3-10, 3-3-11, 3-3-26, 3-3-27, 4-2-15, 4-2-16, 4-2-17, 4-2-18, 4-2-19, Figure 3-3-1A, Figure 3-3-1B, Table 3-3-2, and Table 3-3-5.
This Inspection Requirements document is Federal Aviation Administration, Designated Engineering Representative (FAA DER) approved.
CT Vanes, Page 4, Mar. 31, 1999, Intended for general distribution.
