The Vintage Mechanic

e Vintage Mechanic

ROBERT G. LOCK

C r itic al insp e c tion items

I SE N T OU T E M A IL S to various Travel Air Restorers Association (TARA) members asking for input into what they felt were critical inspection items. Thus far I have received three responses. I am looking for “common threads” that may run through the lists. My task was to compile a list of 10 critical items, publish that list in TARA’s newsletter, and then add to the list as other concerns appear. These additional concerns can be added at a later date, but I want to get things going. We will only be helping ourselves by getting information like this out to members now. By publishing these critical inspection items and proactively addressing them during maintenance, there should be little or no need for future airworthiness directives (AD) notes on these old airplanes. In other words, the Federal Aviation Administration (FAA) is allowing us to “police” our own airplanes for critical airworthiness issues. I think that is much better than facing possible future AD notes. While this list is specific to the Travel Air, it can serve as a “brain teaser” for you as you create your own critical inspection item list for your favorite airplane. So let’s get with the program.

The old Civil Aeronautics Administration (CAA) airworthiness maintenance bulletins were the first attempt to warn owners of potential hazardous problems with their aircraft. These bulletins apparently began in 1938. Today they are airworthiness directives, or AD notes (FAR Part 39).

I will rely on some fine work forwarded to me by Phil Wyels and will duplicate it here in this column. For further information, contact the Travel Air Restorers Association.

The following is quoted from Phil Wyels.

There are no airworthiness directives listed in FAR Part 39 applicable to the Travel Air or Curtiss Wright Travel Air. There were the equivalent of today’s AD notes issued by the CAA. These were titled airworthiness maintenance bulletins. The three of which the writer has a copy are:

Bulletin 8 dated 4-11-39. Subject: Wing to center section spar fitting; early model 2000, 3000, and 4000 with single vertical bolt.

Bulletin 30 dated 7-13-40. Subject: Axle inspection and reinforcement; B series with outrigger landing gear.

Bulletin 51 dated 6-10-41. Subject: Rear safety belt attachment; applies to all Travel Air aircraft.

MODE L ATC* SPE C I A L N O T E S

D-4-D 6-B 10-D 2-178 352 278

12-K 12-Q 12-W 406 401 407

A-14-D

442 15-C 426 16-E 463

16-K 411

16-W 429 11

2

12

10, 19, 21 10, 12, 19, 21 10, 12, 19, 21 12

22

10, 17, 19, 21 10, 19, 21 10, 19, 21 2000 30 11, 20, 23 2000 2-42 11, 20, 23

SC-2000 111 11, 20, 23 2000-T 2-368 9, 11, 20, 23 3000 31 9, 11, 23 4000 32 9, 11, 20, 23

A-4000 148 11, 20, 23

B-4000 146 11, 13, 20, 23

B9-4000 2-381 11, 13, 20, 23

C-4000 149 9, 11, 20, 23

D-4000 2-84 11, 20, 23

E-4000 188 11, 20, 23

K-4000 205 11, 20, 23

W-4000 112 11, 20, 23

W-4000 2-35 11, 20, 23 6000 100 2

A-6000-A 116 2, 12

A-6000-A 2-76 2, 12 A-6000-A SP 2-308 2, 12 SA-6000-A 175 2

S-6000-B 130 2, 12 S-6000-B SP 2-302 2, 12

*ATC numb ers w ith 2-xxx indic ate a Gro up 2 A pproval.

The CAA also issued a document titled “Changes in Aircraft Specification,” which in later issues were titled “Aircraft Maintenance Inspection Notes for Curtiss-Wright Aircraft.” The latest copy the writer has is No A-1231 dated July 7, 1941. The introduction states, “Supplements Aircraft Specifications for all models listed below. Inspectors must report compliance in accordance with the current Certification and Inspection Division instructions covering special inspection procedures.” Thirty-three Travel Air and Curtiss-Wright Travel Air models, each certificated under a di erent ATC or Group 2 Approval, are listed. The writer is of the opinion that these should be treated the same as a recurring AD.

Periodic (Annual) Inspection Required for the Following Notes:

SPECIAL NOTE 2: November 5, 1930. Open fabric under fuselage or remove floorboard and check for failure of dual control column socket.

SPECIAL NOTE 9: February 18, 1938. On airplanes equipped with Bendix 30-by-5 inch wheels, determine that the hub cap bolt extends through outboard wheel adapter and axle proper; or in case axle tube is short and hub cap bolt goes through wheel adapter only, make sure that the adapter is welded to the axle proper around the entire circumference instead of by only a few spot welds, as found in the field.

SPECIAL NOTE 10: October 20, 1938. Inspect U-shaped center section diagonal wire fitting at upper front spar for cracks at the base of the flange. Faulty fittings must be replaced and defects reported on the usual form.

SPECIAL NOTE 11: October 20, 1938, revised March 6, 1939, and June 15, 1940. Ascertain that inspection has been made and entry has been made in logbook in accordance with Airworthiness Maintenance Bulletin No. 8. (Model D-4-D added September 10, 1940.) • Inspect the stabilizer connecting tube forward through the bolt attachment for o -center location and/or elongation of the holes in both the stabilizer leading edge tube and the internal cross tube.

Inspect the bolt for wear.

• Inspect rudder and elevator cables in the fuselage aft of pilot’s seat for chafing on each of the bulkhead brace wires. If the tailskid has been replaced by a tail wheel, check the wires for chafing against the tail wheel and support structure.

• The early 30-by-5 wheels used brass bushings instead of bearings between hub and axle. Check these wheels with the weight removed for side play wobble.

• Check the stabilizer adjustment lever for positive seating of the pin in the quadrant slot when plunger is released. This check should be performed under simulated air loads on stabilizer.

SPECIAL NOTE 12: January 7, 1939. Ascertain that the inspection and safetying of the shock absorbers has been accomplished in accordance with Maintenance Bulletin No. 4. A copy of this bulletin has been forwarded to all owners and inspectors.

SPECIAL NOTE 13: March 23, 1939. Inspect the aileron hinge bracket on the wing for cracks in the vicinity of hinge pin lugs. The ailerons should be removed to facilitate this inspection. In case defects are found, brackets must be replaced with sti er ones, preferably made from 0.065-inch thick X4130 steel.

SPECIAL NOTE 17: July 31, 1940. Ascertain that the shock absorbers, piston head, and packing gland nut of the cylinder are safetied in a positive manner. In this connection, Airworthiness Maintenance Bulletin No. 4 should be considered as also applying to the Model 16-E. SPECIAL NOTE 18: July 31, 1940. Ascertain that the logbook carries a record of inspection or rework of the landing gear axle in accordance with Airworthiness Maintenance Bulletin No. 30.

SPECIAL NOTE 19: September 10, 1940. Inspect rear stabilizer support fitting for cracks in the weld where streamline tube joins fuselage longeron. If defects are found, repair and reinforce by welding finger straps (0.065 inch X4130) on both sides of fitting, with fingers extending along streamline tube and fuselage longerons.

SPECIAL NOTE 20: November 22, 1940. On airplanes with detachable engine mounts, inspect the engine mount members for cracks in the vicinity of the attachment fitting to the fuselage. In case defects are found, the entire end fitting should be replaced.

SPECIAL NOTE 21: February 3, 1941. Inspect the stabilizer front spar for cracks in the vicinity of the root ribs. If defects are found, repair and reinforce with outside sleeve (1-1/4 by 0.049 inch X4130).

SPECIAL NOTE 22: May 2, 1941. Ascertain that portions of the exhaust collector rings inside of the cowling are shielded from the engine accessories compartment by means of ba es extending from the engine ring to the inside periphery of the cowling. Such ba es were originally installed by the manufacturer, and their removal is prohibited. The original engine mount ring is provided with drilled holes for the insertion of such ba es, and the engine cowling is provided with exits for the cooling air, which impinges against the required ba es.

SPECIAL NOTE 23: July 7, 1941. Ascertain that the rear safety belt installation is revised in accordance with Airworthiness Maintenance Bulletin No. 51.

NOTE: If anyone has a copy of Airworthiness Maintenance Bulletin No. 4 or any others not listed, the writer would appreciate a copy to add to TARA files.

From Phil Wyels comes the following list of critical inspection items:

Items to Check When Doing an Annual Inspection on Your Travel Air Aircraft: • The steel tubes at the aft end of a tailwheel aircraft can corrode internally. Check the lower portion of the tail post, both longerons in the last bay, and the elevator torque tube. These have been areas where moisture accumulates. Punch test the tube at 1-inch intervals using a

Maule fabric tester or an ice pick.

• If your Travel Air has pulleys installed in a control system, inspect the pulleys for wear in the groove and the cable for broken strands where it rides on the pulley. (AN type pulleys presently may not be used in a control system where the bend in control cable is more than 30 degrees. Prior to 1941, a 2-7/8inch pulley could be used.)

• If your Travel Air still has return springs attached to the rudder pedals, they should be inspected for grooving at the attach points and for rust corrosion.

And now a list as prepared by Bob Lock: Critical Inspection Items for Travel Air Airplanes: • Structural Considerations: All major attachment points for security and cracks. Streamline wires for correct tension (looseness could indicate possible internal structural problems). Wood deterioration, particularly lower wings at wing-walk trailing edge. Any suspicious wrinkles in fabric at any location could mean possible internal problems. Landing gear attach points for wear/cracks. Shock cords for condition (replace cords before they stretch and/or break).

• Seats and Restraint Systems: Seats firmly attached to structure. Seat belt/shoulder harness attachment points secure. Belts/harness for chafing. Locking devices (if any) are positive and work freely.

• Trim System: Excessive wear on trim sector and handle. Cable tension correct. Excessive looseness (slop) in stabilizer (up and down, sideways). Tension on brace wires.

Lube hinge points.

• Primary Flight Controls: Excessive looseness (slop) from cockpit control to surface. Push/pull tubes and cables for wear/damage (always set/check cable tensions with surface in neutral position). Lube all hinge points.

• Fuel System: Evidence of leaks and chafing of fuel lines. Positive movement of selector/shut-o valve. No fuel flow with valve(s) in OFF position.

• Oil System: Leaks and chafing of lines. Tank hold-down straps for security and cracks. Hoses for cracking/deterioration and clamps tight.

• Engine Controls: Full range of travel and “spring back” on cockpit control when stop is reached.

Condition of control ends.

Eliminate any excess movement.

Carb heat for proper operation and condition of air filter.

• Main wheels: Closely inspect Bendix 30-by-5 wheels for cracks or loose rivets. It will be necessary to jack aircraft, deflate tire, and break bead.

Move the tire bead in to inspect rivet heads around rim. It’s a pain to do this but well worth the e ort if loose rivets or cracks are found. Also check inner and outer spinnings for dents or other damage.

• Tail Wheel, Steering/Locking: Tire for correct inflation and check wear pattern. Steerable assembly:

Check for positive movement with rudder, springs snug, positive locking in “trail” position. Locking assembly: Check for positive lock/ unlock, shock strut condition, servicing, and lubrication points.

• Tires: Check for wear patterns; when wear pattern becomes visible, remove and reverse tires.

Always replace tube when replacing tire. Never allow cord to show.

• Brakes: A most important item that must always work and work well.

• Mechanical: Cables and pulleys (metallic pulleys should always be used), return springs, lubrication of assembly, lining and drum condition.

• Hydraulic: Leaks, correct fluid type used for servicing, return springs, lubrication of moving parts, condition of lining and drums (check for out-of-round; if they’re out-ofround, the brakes may “grab”).

This commences our listing of the most critical inspection items on Travel Air and Curtiss-Wright Travel Air aircraft. The list will expand with time, and we will continue to publish the data as it is received and compiled. My thanks go to Phil Wyels for his input into this column. Any owner/ operators, mechanics, or inspectors are encouraged to file your list of critical inspection items for Travel Air airplanes. You may send the lists to the association, and the lists will find their way to me. Thanks in advance for all your help in keeping owners, pilots, and our aircraft safe. If you have a task that you feel is a critical inspection item on a di erent type of aircraft, and you think it’s generic to most other vintage airplanes, send it along.

Also included in this article is an example of an old CAA airworthiness maintenance inspection notes dated November 6, 1942. It concerns Command-Aire Model 3C3 aircraft and is signed by the ship’s original designer, Albert A. Vollmecke. Note that Albert was division chief of the CAA (later the FAA), a position he occupied until his retirement from the FAA in 1968.