University of Alabama

Flight Dynamics Laboratory

Mini500 Helicopter

Operations Log



25 Mar 2000  Engine started for the first time and broken in bY Mr. Joe Green
 Hobbs time  and Mr. Gary Nash. 5 gal of fuel mixed with oil were used, and 
  0.1-0.6    then 5 gals without oil poured in.

04 Apr 2000  Aircraft inspected by DAR Mr. John Burgin and issued certificate
             of airworthiness and operating limitations.

06 Apr 2000  7.5 lb of lead shot added as ballast to the front of each skid.
Engine time  Ballast contained in burlap "socks," poured in place. When full,
  1.6-2.0    sock expands and friction maintains it in place.

             Cyclic adjustment: rear control rod #165 shortened to move cyclic
             travel range aft and prevent cyclic handle from making contact
             with instrument panel.

             Aircraft was fueled with 5 gal of fuel mixed with oil. Level of
             oil in tank was marked with green tape.

             Engine was started and hover trials made with A. Katz at the
             controls. 

                
It was verified that oil level in oil tank dropped. Discrepancies: Engine tachometer off. EIS indicates correct engine RPM. Input disconnected from EIS, but problem persisted. Coolant temperature reading reduced when EIS is on. This input disconnected from EIS. No EGT indication. Wiring fault corrected. Started the installation of the balancer. Photo tach attached to front of turtle deck with duct tape. 2" of relective tape attached to bottom of blade A. Could not attach accelerometer because the self tapping screw used on the bottom of the windshield trim was oversize. Post-flight inspection: Belt moved fwd and now is at edge of transmission wheel. 07 Apr 2000 Attached accelerometer to aircraft nose with 3/16" machine screw secured by nut & 2 washers. 11 Apr 2000 Cyclic can still be forced into contact with instrument panel by Engine time bending. Rear control rod #165 shortened further to move cyclic 2.0-2.4 travel range aft and prevent contact with instrument panel. Belt tracking adjusted to leave 1/8" margin at front of transmission wheel. Belt tension rechecked. A piece of duct tape was attached to blade B to balance the reflecting tape on blade A. Engine was started and the following procedures carried out on the ground and in hover: Adjusted engine tach to agree with rotor tach approximately. Exact agreement not attained. Tried balancer on ground. RPM readings too high (~13K). Removed duct tape from blade B. Got correct RPM (546) and sample vibration reading on ground. In hover, RPM not correct. Did not get hover vib readings because collective tends to rise, if left alone, and access to balancer button difficult. Flight operations aborted when drive belt became frayed. This resulted from the nut #463 becoming loose and falling off the drive idler arm screw #205. The nut was recovered. Partial disassembly was begun to allow replacement of the drive belt. Rear control rod #165, clutch bearing housing #209 and tension barrels #133 (2) removed. The tail rotor drive was separated from the coupler plate. The tail, tail rotor transmission and tail rotor were also removed. However, this still did not allow the drive belt to be taken out.
13 Apr 2000 Disconnected lower attach points of rear mast support arms. 2.4 Removed the two eyebolts that attach the tail boom to the frame. Also disconnected upper left tail boom support from frame at firewall. With this done, the worn drive belt was removed. The tail parts previously removed unnecessarily (tail transmission and rotor and tail surfaces, were reattached to the tail boom. The drive belt was identified as B1200AM50 (1200mm circumference, 50 mm wide.) A replacement was ordered from Power & Rubber Supply Co. of Tuscaloosa. Oil drained from tail rotor transmission and not refilled for lack of a measuring cup.
18 Apr 2000 New drive belt installed. Tail boom reconnected (bolts and Engine time eyelets secured with blue locktite). Rear mast support arms 2.4-3.0 reconnected. Clutch support plates reinstalled and safety wired. Tension barrels reinstalled. Rear control rod reinstalled. Belt tension adjusted and checked. Belt idler secured with a nylock nut. Tail transmission filled with 3+ ounces of transmission oil. 5 gals of fuel without oil added to tank. The engine was started and the aircraft was hovered includeing hover taxi and hover turns. A second flight used to attempt a measurement of vibration level. Levels ranging from 0.35ips to 1.5 ips were indicated depending on wind condition and flight condition. However, no tach reading or wrong tach reading most of the time. Balancer reads photocell correctly during static checks. 22 Apr 2000 Trouble shooting session: Engine time * Determined that crack between air filter and holder does not 3.0-3.2 admit air into carburetors. * Determined that Hobbs meter not powered thru either master or avionics master switch. Rather, it is powered directly from the rectifier. This way, it records engine time. * Corrected error in wiring of EGT wires. EGT gages now work. * Lengthened tension barrels, after which spinning rotor by hand moves belt to 1/8" aft of edge of transmission gear. Vibration level in flight low. After shut down, belt at edge again. Spinning rotor by hand brings it back to 1/8" behind edge. * Adjusted engine tach to agree with rotor tach at 100%. * Reinstalled photocell unit of balancer with masking tape painted black on both blades and the reflective tape on top of the masking tape. Now balancer reads correctly both on the ground and in hover. Too windy to collect balance data. 28 Apr 2000 Hover demo for AEM Advisory board. Windy conditions. Vibration Engine time level high. 3.2-3.3 11 Jun 2000 Photo session with J. Lipkin. Hover taxi & turns. Vibration level 3.3-3.5 low. 14 Jun 2000 Hover maneuvers. Could not take vibration readings because 3.5-3.8 balancer dead. Vibration level low. 16 Jun 2000 Hover maneuvers. Flight time 0.8. Rest of time spent trying to 3.8-5.0 make balancer work. RPM reads too high most of the time (e.g., ~3000 instead of 118). Reblackened masking tape. blackened additional area on blades. replaced reflective tape, replaced balancer battery, repositioned photocel -- no luck. Cloudy day with occasional sprinkle, wind. Vibration average measurements taken (azimuth meaningles): First flight Second flight 0.19 172 0.06 336 0.48 285 0.21 68 0.13 341 0.16 162 0.29 306 0.27 331 0.35 279 23 Jun 2000 Hover maneuvers. Balancer still does not work. Sky was fair with 5.0-5.3 some high clouds. Large drop in engine RPM indication on right mag (has been this way). Rotor RPM unaffected. Exhaust gas temp remains normal for both cylinders. Hovered on right mag -- no effect on power. Throttle friction adjusted (in engine compartment). Throttle still tends to roll off when left alone, but remains stable with hand resting on it. 26 Jun 2000 Balancer with photocell unit & cable shipped to manufacturer for 5.3 inspection. 28 Jun 2000 Replaced oil in main & tail transmissions. Topped off coolant. 5.3 30 Jun 2000 Balancer returned with replacement photocell unit & cable.
02 Jul 2000 New photocell unit installed on helicopter. Balancer now works. 5.3-5.7 The following averaged readings obtained: In hover at altitude AGL Vib level Azimuth (ft) (ips) (deg) ------------------------------- 0 0.80 280 ............................ 2 0.86 202 5 0.75 204 10 0.87 196 Azimuth is close to the hub weight shift line. Sensitivity quoted in manual as 0.0279 ips/g. Need approx. 30g on blade B. 03 Jul 2000 Replaced washers at both ends of outboard bolt (#407) with 5.7 oversize washers. Replacement washers weighs 16g, original weighs 2g. Added weight 28g. 04 Jul 2000 Vibration averaged readings taken under windless conditions: 5.7-6.1 In hover at altitude AGL Vib level Azimuth Sensitivity (ft) (ips) (deg) (ips/g) --------------------------------------------- 0 0.45 296 0 0.16 254 ....................................... 2 0.39 224 0.0168 5 0.36 220 0.0139 10 0.31 215 0.0200 ---------- Average 0.0169 Sensitivity less than published. Direction of move ~180 deg vs The published 200. More mass needed on blade B. 07 Jul 2000 Replaced bolt #407 (40g) on blade B by a longer AN6-25 (45g). 6.1-7.1 Installed with one regular washer and one oversize washer (30g) on top and two on the bottom, altogether ~35g increase. Vibration averaged readings taken under windless conditions: In hover at altitude AGL Vib level Azimuth Sensitivity (ft) (ips) (deg) (ips/g) --------------------------------------------- 0 0.24 358 .......................... 2 0.12 315 5 0.11 299 10 0.09 329 Added 2 oversize washers to bolt #369 at pitch link on blade B. Vibration averaged readings taken under near windless conditions: In hover at altitude AGL Vib level Azimuth Sensitivity (ft) (ips) (deg) (ips/g) --------------------------------------------- 0 0.38 280 .......................... 2 0.06 309 5 0.07 283 10 0.06 330 With all readings below 0.1ips, the main rotor is balanced for 1 per rev vibrations.
10 Jul 2000 Moved balancer to tail rotor and installed on left front bolt of 7.1-7.8 tail rotor transmission using the bracket supplied with the new photocell. A square of reflective tape was placed on tail rotor hub plate (#56) on the blade A side and a similar square of duct tape at blade B. Vibration measurements were taken on the ground with rotor RPM at top of green, flat pitch, cyclic and pedals centered. Vibration averaged readings taken under near windless conditions: Vibration level (ips) azimuth (deg) ---------------------------------------- 0.50 339 0.35 338 0.40 345 Removed from B cordwise large washer and replaced with ordinary washer Vibration level (ips) azimuth (deg) ---------------------------------------- 0.38 326 0.36 322 0.29 314 0.32 322 Remove the whole bolt holding chordwise weight on B side Vibration level (ips) azimuth (deg) ---------------------------------------- 0.50 296 0.39 279 Conclusion: with this installation, move is at 45 deg to that indicated in manual. At this point put spanwise weight on blade A by replacing washer with an oversize washer Vibration level (ips) azimuth (deg) ---------------------------------------- 0.23 190 0.28 190 0.24 198 This move also shifted 45 deg. Now backed up on chordwise weight by returning bolt and spacer and installing with lightweight washer. Vibration level (ips) azimuth (deg) ---------------------------------------- 0.09 143 0.08 154 0.13 153 0.10 159 0.12 149 0.04 163 Now backed a little on spanwise weight by adding second regular washer on blade B. Vibration level (ips) azimuth (deg) ---------------------------------------- 0.06 217 0.06 263 0.03 266 At this point tail rotor is balanced. Returned balancer to main rotor.
11 Jul 2000 Verified balancer operation. Then, with reflective strips on both 7.8-8.6 blades took 2/rev (1/blade) readings. Avg in hover: Vibration level (ips) azimuth (deg) ---------------------------------------- 0.53 100 0.79 122 0.84 123 0.61 111 Vib level increases in fwd motion to 1.2-1.5. In slow rearward motion or when stopping it drops to 0.25-0.35, picks up again as rearward motion accelerates. 13 Jul 2000 Approximate Azimuth of 2/rev vs direction of translation in hover: 8.6-9.2 Fwd Left Aft Right Reading 140 40 300 200 Coning* 180 90 360 270 Residual+ 270 180 90 0 Differences from coning -40 -50 -60 -70 from residual -130 -140 -150 -160 Results appear consistent with insufficient undersling.
20 Jul 2000 Mounted teeter balance brackets on hub plates (#12) by bolts #398 9.2-9.9 with washers removed. Each teeter plate weighs 165g. On the ground (collective down) vibration level was 0.82 ips, and the azimuth as a function of cyclic stick deflection was Cyclic input Fwd Left Aft Right Azimuth 180 45 340 260 Coning* 180 90 360 270 Residual+ 270 180 90 0 Differences from coning 0 -45 -20 -10 0.91 from residual -90 -135 -110 -100 -0.31 In stationary hover in a light wind took average 1/blade vibration measurements with different headings: Wind from: Fwd Left Aft Right Average Vib level (ips) 0.64 0.66 0.13 0.93 Cosine Azimuth 71 64 252 185 Coning* 180 90 360 270 Residual+ 270 180 90 0 Differences from coning -109 -26 -108 -85 = 0.088 from residual 161 -116 162 -175 = -0.83 Average from coning *"Coning" is for inertial effect due to insufficient undersling. +"Residual" is due to residual bending. Interpretation: resonant mode at 1.69Omega (vs 1.25Omega for original Mini500, 1.49Omega for one with Revolution mast support.) For rotor tilted forward, azimuth readings associated with coning and residual (2 per rev) are: drive response Coning 180 31 Residual 270 121 Measured response is at ~70, being combination of both. Need to lower rotor CG further to eliminate coning effect. 28 Jul 2000 Took measurements in hover in no wind or light & variable. The 9.9-11.1 purpose was to reestablish previous result. However, results scattered: Hvering at 2 ft (averaged readings): level (ips) 1.02 0.55 0.85 0.66 0.31 0.53 0.53 0.83 azimuth 119 107 135 143 120 166 140 97 Hvering at 10 ft (averaged readings): level (ips) 0.52 0.62 0.66 azimuth 91 72 32 Added a bolt with 14 washers & locknut at one lowest hole on the teeter bracket on each side. Added mass 55g.
Hvering at 10 ft (averaged readings): level (ips) 0.35 0.77 1.07 0.80 0.60 0.53 azimuth 125 149 145 124 132 129
Subjectively things appear smoother with added weight. Still very noticeable increase of vibration in fwd motion. Readings well above 1.0, subjective feeling of lateral vibration. 30 Jul 2000 Removed turtle deck and inspected underneath. Found drive belt 11.1 slightly over edge of transmission gear. Lengthened each of the clutch tension barrels (#133) by one turn. Found two cracks starting in lower rear of turtle deck. 31 Jul 2000 Adjusted belt tension (adjusment amounted to one turn of lock 11.1-11.9 nut). Stop drilled cracks in turtle deck. Took two per rev vibration readings in stationary hover in 4 knot wind: facing wind: level (ips) 1.45 1.40 1.98 1.39 ------------------------------------------ azimuth (deg) 114 103 81 111 with back to wind level (ips) 0.19 0.83 0.56 ----------------------------------- azimuth (deg) 170 183 137
Went about 3000 ft on taxiway 04 and back. Reached indicated airspeed of 45 knots. Saw 2/rev vib levels up to 3.25. Highest levels around ETL, then back down to ~1.7. Drive belt moved slightly over front of transmission gear. 05 Aug 2000 Removed turtle deck and inspected underneath. Shortened each of 11.9 the clutch tension barrels (#133) until top of clutch support plates #206 & #207 was parallel to transmission and adjusted belt tension. In the process, belt moved well aft of front edge of transmission gear. 09 Aug 2000 In no wind condition tried effect of ballast at the nose on 2/rev 11.9-12.2 levels. Ballast was initially at firewall, then moved to nose. Average readings: Ballast level Azimuth (kg) (ips) (deg) 0 0.67 93 7.660 0.46 77 4.735 0.46 67 Drive belt moved forward and was damaged. Heard 3 pops, and put helicopter down. Smelled oil. There was oil on and near the clutch. 10 Aug 2000 Oil came from transmission through bearing of the drive gear. 12.2 Changed the transmission oil. The transmission was nearly full. Left a cup in place to catch any flow, but there seems not to be any. 12 Aug 2000 Fuel leak developed at bottom of sight gage line. Fuel created 12.2 puddle on floor of cabin. Fixed leak by moving and retightening clamp. Drilled a drain hole at bottom of cabin. Collected ~1.5 gal of fuel. Removed damaged drive belt using following procedure: 1. Reduced belt tension by moving idler out of the way as far as it can go. 2. Disconnected drive plate (#119) from both transmission and tail rotor drive shaft. 3. Disconnected bottom ends of rear mast support arms from eyebolts. 4. Provided external support for tail boom. 5. Removed eybolts (they hold the tail boom attach plate to airframe.) 6. Undid bolt that holds left upper tail boom support to top of airframe near firewall. 7. Now tail boom could be maneuvered to provide enough space to remove drive plate (#119). The drive belt was also slipped through the same space and now encircled only the lower pulley near the clutch. 8. Removed the four bolts (2 on each side) that hold clutch bearing housing (#209) to the clutch support plates (#206,207). 9. Loosened the 4 bolts that attach the clutch support plates (#206,207) to the engine. 10. This provided enough play so that the clutch bearing housing (#209) could be turned 90 degrees, creating the necessary opening to remove the drive belt. 18 Aug 2000 Installed new drive belt: 12.2 1. Threaded new belt in place on pulleys. 2. Returned drive plate #119 into place and connected to tail rotor side. 3. Reconnected left upper tail boom support to frame (blue lt). 4. Reconnected tail boom attach plate to frame using eyebolts (blue lt). 5. Reconnected lower end of rear mast support arms to eyebolts. 6. Reinserted 4 bolts that hold clutch support plates (#206.207) to clutch bearing housing (#2309). Tightened these bolts and the four bolts thet hold clutch support plates (#206.207) to the engine. 7. Reconnected drive plate (#119) to transmission side. 21 Aug 2000 Safety wired bolts that hold clutch bearing housing (#2309). 12.2 Safety wired main transmission drain plug & tail transmission fill plug. Checked that clutch bearing housing (#2309) is vertically parallel to mast. This required no load in clutch tension barrels #133. Could not check directly that power pulley is parallel to transmission pulley for lack of a small enough level. Idler slopes slightly down toward front. 25 Aug 2000 Aligned Idler to be parallel to transmission pulley as measured 12.2 by level on each. This was accomplished by reworking holes where idler support connects to frame and by deforming idler support arm with a metal bar. Belt tension set and alignments rechecked and readjusted with tension on. 28 Aug 2000 Monitored belt track and transmission oil leak on the ground and 12.2-12.6 in hover with help of T. Waits. Belt stable behind edge of pulley. Oil leaks from rear end of transmission. Drop collects on rear underside of transmission and eventually drops onto clutch. Flow increases as transmission heats up.
03 Sep 2000 Arranged cup to collect dripping oil. Over 24 hours, a few drops 12.6-13.1 collected. During today's hover flight 0.1", which computes to 3.2 cc. This temporary measure should permit continued work on 2/rev pending replacement of seal and o-ring. Data taken in hover with 4.735 kg ballast (averaged): level (ips) Azimuth (deg) ------------------------- 0.29 91 0.42 82 0.43 99
11 Sep 2000 Took 2/rev measurements in hover with both ballast bags in place, 13.1-14.0 12.395 kg total. At the beginning, there was no wind. Data A were taken facing NE at open end of apron. Data B were taken facing parking lot and low building (hdg N). Two of the measurements C were then taken back where A was taken. It appears that lower vibration levels not due to location and heading but rather to warmup of transmission. Toward end of session, the official wind was 110 at 4. Levels recorded facing east (D) were higher than the ones taken facing west, but not as high as the initial measurements A. A: level (ips) Azimuth (deg) Heading: NE ------------------------- 0.37 39 0.30 28 0.30 35 0.32 31 B: level (ips) Azimuth (deg) Heading N ------------------------- 0.16 10 0.20 38 0.04 182 0.09 289 C: level (ips) Azimuth (deg) Heading ------------------------------------ 0.14 15 NE 0.07 26 NE 0.08 1 SW D: level (ips) Azimuth (deg) ------------------------- 0.27 17 110 0.19 40 110 Problems: 1. Ballast dropped off from console a couple of times. need a method to retain it. 2. Oil catcher dislodged from clutch tension barrels and dropped onto radiator shroud. It was not possible to monitor loss of transmission oil, but amount spilled is consistent with rate of 6.5 cc/hr. 14 Sep 2000 All ballast (about 27 lb) placed in black belly bag and attached 14.0 semi-permanently to front of console ahead of instrument box and EIS. 15 Sep 2000 New metal oil catcher installed. It is made of an AL strip and 14.0 attached to clutch tension barrels with clamps held by #8 screws, which attach to threaded holes in aluminum strip and are secured by jam nuts with lock washers.
Any flight at appreciable forward speed must be made with left engine compartment door attached, otherwise the airflow will damage the carburetor housing (#333). (This was not done on 31 July, and no damage occured at 45 knots. However, longer exposure and/or higher speed are sure to cause damage.) Inspected fuel tank and found the cause of the sagging. The inboard loop clamp (#559) lost its rubber and slid down the frame member. This allowed the tank to slide aft down and out. The tank heat shield lodged behind the front EGT probe housing on the exhaust manifold. The tank was returned to proper position and secured by a hose clamp on the frame member. The tank heat shield now maintains a small clearance from the exhaust manifold. It is possible to install the right engine compartment door, however, the door makes contact with the side of the tank. The seat-attachment nuts on the left (2) came off and were found on the cabin floor. The seat was not at the forward position as originally set, but, rather, close to the aft position. This must have been its position on recent flights. The seat was moved full aft and the nuts were secured. 18 Sep 2000 Put left engine compartment door on and kept right door off (cabin 14.0-14.6 doors both off). Made hover test of oil catcher. Air taxied the length of taxiway A and back at up to 55 knots. 2/rev levels up to 1.6 ips in transition, then settled to less than 1. Made 1 traffic pattern at 600' AGL at 50 knots. This was the FIRST TRAFFIC PATTERN for this aircraft. Saw levels up to 1.25 in climb, then settled to ~0.75. Post flight inspction showed that oil catcher cup separated. The aluminum strip remained attached but slidd down on right tension barrel. 20 Sep 2000 Oil cattcher repair: Clamps on both sides of the AL strip 14.6 tightened. Middle of strip coated with duct tape with embedded wire bhind to stabilize cup under vibration. 22 Sep 2000 AUTOROTATION TEST performed today. Autorotated from ~2000' AGL to 14.6-14.9 ~1000' AGL. With collective full down, rotor overspeeds and I run out of aft cyclic. Both problems cured by raising collective slightly. No change in rigging needed. In climb, read 2/rev vibration levels in excess of 2 ips. Can reduce level by slowing down or by reducing climb rate. I may be working engine too hard. Without manifold pressure it is hard to tell. Temperatures well in green. Post flight inspection found no discrepancies. Oil catcher of 20 Sep remained intact and contained 2cc. 28 Sep 2000 Horizontal stabilizer was modified by cutting off part behind 14.9-15.7 mounting plates #88 and #98. Winglets left out. Flew about ten traffic patterns in new configuration. Less objectionable side to side shaking, but balancer still indicates vertical 1.5ips in climb.