Viewing page 168 of 507

This transcription has been completed. Contact us with corrections.

160          HELICOPTER AIR SERVICE PROGRAM

(a) A 50-inch forward cabin extension, permitting the installation of additional rows of seats.
(b) Long spindle tail rotor assembly, permitting 1,000 hours TBO.
(c) Cabin vibration absorbers.
(d) Specially designed airstair and cargo loading door.
(e) "BIM" equipped main rotor blades.
(f) The quick exchange pod program. (Two "sliding drawer" type baggage pods, having capacities of 600 pounds each, are installed below and [?] of the port side cockpit floor of the S-61L. Not only do these make available much needed additional cabin space, but their ultimate quick exchange capabilities (using mobile carriers) will be highly significant in perfecting rapid turnaround at heliports. It should be noted that during a 3-minute turnaround period, over 50 "on and off" passengers, plus baggage, express and mail, must be managed.)

Some aspects of the above design changes, such as the extension of the fuselage, have been directly used in military aircraft. (See testimony of Sikorsky Aircraft expert, attached.)

PRODUCT ENGINEERING

Because of its high utilization, LAA's fleet of aircraft has been used by the General Electric Co., and Sikorsky Aircraft as an extension of their engineering development activity. This is particularly significant because of the commonality between military and commercial helicopters of the S-61 series, where in general identical engines and components are used.

The principal problems common to aircraft in use at LAA and in the military services are (a) powerplant, (b) main transmission, (c) fuel system, etc. LAA's experience has achieved "fixes" in these areas in the following examples:

1. Vibration is power turbine causing bearing housing failures and damage to power turbine blades (cost - approximately $18,000 per engine or $500,000 totally to LAA).
Problem corrected by engine modification and vibration damper installed on engine support.

2. Failures in main transmission (gearbox) were occurring due to breakage of teeth on the bevel gear. There have been 11 failures of this type. (Cost to LAA of 9 failures between March 1962 and July 1964, $109,900.)

3. Failure of fuel cells due to leaks. (Cost of removal and repair of cells to date $11,868 with aircraft out of service 2 to 4 days.)

Problem corrected by redesign, with no subsequent failures.

The benefit of LAA's experience in this area has been made available to manufacturers for dissemination to military services.

PRODUCT IMPROVEMENT

Every turbine engine installed at LAA has been used as an evaluating engine "test bed" in the General Electric small aircraft engine products improvement program.

This program has included the installation of hundreds of parts into LAA's engine, which were then evaluated under accelerated operating conditions. Several installations resulted in successful "fixes" of problems. Others were rejected as representing insufficient improvement.

Many of the completed improvements are now fitted in all T-58 engines, and specific instructions for their installation are to be found in General Electric engine bulletins.

Several of the LAA evaluation items, and their "fixes," procedures and techniques have been, or are now being installed in military T-58 engines. The table at end of appendix B illustrates certain improvements to the T-58 engine directly attributable to experience gained in commercial operation at LAA, and shows the appropriate military published instructions.

Certain items listed in the table have had a major effect on engine availability and on overall reduction of costs. Discussed in detail below, for example, is item 8, "Stator vane schedule upspeeding."

Stator vane schedule upspeeding reduces the probability of turbine engine compressor stall. If a stall occurs, there may be a reported engine over temperature, or an actual overtempterature condition. It costs the carrier approximately $1,000 to determine whether this condition actually occurred, since the engine must be substantially dismantled and hardness tests performed on the metallic structure